linguistic underdetermination thesis

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19 Underdetermination by Reasons

Joshua Gert is Leslie and Naomi Legum Professor of Philosophy at The College of William and Mary. His work on rationality and reasons includes Brute Rationality (Cambridge University Press, 2004) and Normative Bedrock (Oxford University Press, 2012).

• Published: 10 July 2018
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The norms of rationality determine whether an act is irrational, rationally required, or rationally optional. It has seemed theoretically difficult to make significant room for the last category, because rational status is typically taken to be a function of reasons, and reasons are typically taken to have univocal strength values. But there is also a strong intuition that normal choice situations present us with many equally rational options. If this intuition is correct, two questions arise. The first is how it could be true, assuming that rational status is indeed a function of reasons. The second is whether and how we can act in a non-arbitrary way when we are faced with a choice between a number of equally rational options. This chapter examines four strategies for addressing these questions: incommensurability of reasons, parity, the ubiquity of ties, and a distinction between the justifying and requiring roles of practical reasons.

One striking implication of old-style hedonistic act utilitarianism is that in most circumstances there is just one action that we ought to perform: the one that produces the greatest quantity of overall happiness. This feature is striking in a moral view because generally we think of morality as giving us considerable leeway regarding all sorts of morally-neutral choices. Should I stay up and finish watching this movie, or go to bed now so that I’ll be fresher tomorrow? Unless someone is going to be depending on my freshness, commonsense morality is silent on this issue. It achieves this silence relatively easily by being, most centrally, a system of prohibitions. Anything not prohibited is allowed, and in many situations there will be no relevant prohibition. Moreover, even moral systems that centrally feature a set of moral rules that function to prohibit certain kinds of behavior typically also include another set of considerations that can justify violations of those rules without requiring them. In cases of justified violations of a moral rule we have a pair of options that are both eligible: (a) the option not to violate, and (b) the option to violate, but with justification. A paradigmatic example of this situation involves the moral rule against harming others, and considerations of self-defense. Self-defense can often justify a violation of this rule, but cannot require it. To sum up: when there is no relevant moral prohibition, there may not be any moral reason of relevance to our choice. And even when there are moral reasons against an action, we may still have the option to act, or not act, on a justification for going against those reasons. Because of all this, it is relatively easy to explain the existence of many morally acceptable options.

Now let us turn our attention from morality to practical rationality. Alas, there is much less agreement on what we are even talking about when we use the term “practical rationality.” So, to be clear, let me say that by “practical rationality” I do not mean to be talking about a mental faculty, but a set of norms that fix the status of an action—as rationally permitted, required, prohibited, etc.—based on the relevant reasons. Moreover, I take those reasons to be facts, not beliefs. There is another quite legitimate sense of “rationality,” which takes more subjective factors into account, so that it would count as perfectly rational to drink a glass of poisoned milk if one were (reasonably) ignorant of the fact that it contained poison. I use the term “subjective rationality” for this notion. Subjective rationality is typically defined in terms of the more objective sense of rationality, so the objective sense is theoretically more basic, and it is this objective sense that is under discussion in what follows. A good heuristic—though, for obvious reasons, not an analysis—for determining whether an act is rational or not in this objective sense is to ask whether any normal person could knowingly intend to perform an act of that type, and could offer reasons that would make sense of that intention.

When thinking about rationality in the sense just described, it is more difficult to explain how it is that we could have a similar leeway. Although there might not always be moral reasons bearing on our choice, there are always reasons of a more generic sort: the sort that are relevant to practical rationality. If one thinks that all reasons are comparable in terms of their strength, it will be tempting to say (in a way that parallels the moral claims of the old-style hedonistic act utilitarian) that the uniquely rational action is the one favored by the strongest set of reasons. If this is right, then except in the rare case of a perfect tie, reason will always determine choice. Despite this, some philosophers have a very strong commitment to what Joseph Raz, in a phrase that does justice to its centrality, calls “the basic belief”: the belief that “most of the time people have a variety of options such that it would accord with reason for them to choose any one of them and it would not be against reason to avoid any of them” ( Raz 1999 : 100). Nor is this only true because most of the time we are not faced with particularly significant choices. As far as the dictates of reasons go, the basic belief might well characterize the decision to have a child or not, or to opt for a very painful life-saving treatment or not. The basic belief is essentially the belief that—typically—reason underdetermines choice.

If one endorses Raz’s basic belief, one then faces two primary theoretical problems. The first is the problem of explaining how it can be true. Given that reasons come with degrees of strength, how can one avoid the conclusion that rational action is simply action on the strongest reasons? The second problem comes once one has solved this first one. Suppose that, in a particular choice situation, one is faced with a wide range of options, none of which is superior to the other in terms of reason. Still, one must typically choose. But how can one do this in a non-arbitrary way, if all the relevant reasons, taken together, do not provide guidance? Of course, this can be interpreted as a practical problem, and expressed by the question: “What should I do, given that all my options are equally eligible?” But it is also a theoretical problem, since it would be a liability for any theory of human action that most such actions had to be viewed as arbitrary, unreasoned, or arational. This chapter will present four of the best-developed strategies for addressing these problems. These strategies depend on the following four theses, respectively: (1) that many reasons are incommensurable or (if it is a distinct relation) imperfectly comparable, (2) that reasons can stem from values that are “on a par,” (3) that cases of perfect ties are much more common than one might think, and (4) that we need to distinguish two dimensions of normative strength: justifying strength and requiring strength.

19.1 Incommensurability

Derek Parfit clearly endorses the idea that it makes sense to talk about the strength or weight of reasons, and also that it makes sense to talk about sets of reasons combining their strength or weight so that together they outweigh some other opposed reason. He is also happy to talk about what we have most reason to do, and to claim that when one option is what we have most reason to do, then the reasons that favor it are decisive . Given his endorsement of these ideas, one might expect Parfit to hold that there is (at least typically) just one act that we have decisive reason to perform. But he is explicit in his denial of this claim, and he is also explicit in holding that the existence of multiple options, none of which is favored by decisive reasons, is not the result of ties in the strength of the opposed reasons. Rather, his view is that although reasons come with strengths, truths about the relative strengths of distinct reasons are often very imprecise ( Parfit 2011 : 32–3). To give a clearer idea of this sort of imprecision, Parfit makes some claims about the degree with which we can compare personal reasons with impartial reasons. Here are paraphrases of two such claims:

The precision with which we can compare the personal reason for me to save my own finger as against the impartial reason to save the life of a stranger does not allow us to say that one of these reasons is stronger than the other. As a result it is plausible that we have sufficient reason to act in either way. The precision with which we can compare the personal reason for me to save my own life as against the impartial reason to save the life of one stranger does not allow us to say that the reason to save my own life is stronger or weaker than the reasons to save two strangers or to save two thousand strangers. ( Parfit 2011 : 137–8)

Despite the extreme latitude given by the relevant imprecision here, Parfit does think that personal and impartial reasons are comparable to some minimal degree. For example, he claims that we have decisive reason to save a million people from death or agony even if the cost is some mild discomfort for ourselves ( Parfit 2011 : 135).

The latitude given by the lack of precision of the normative facts relevant to choice seems to pose the same sort of problem for Parfit that Parfit identifies in Sidgwick’s view. On Sidgwick’s view duty and self-interest are completely incommensurable. Because of this, reason cannot help us help resolve conflicts between them ( Parfit 2011 : 142). Parfit calls this “the rationalist’s problem.” In identifying this as a problem for Sidgwick, one might think Parfit takes his own view to provide a solution. But I do not think this is true. Parfit’s wide value-based objective view of reasons—according to which we have imperfectly comparable impartial reasons and personal reasons—( Parfit 2011 : 137, 382) also gives rise to the rationalist’s problem. And, despite the fact that Parfit is sometimes read as a strong moral rationalist ( Setiya 2011 : 1287), he nowhere attempts to solve the rationalist’s problem, or claims that it can be solved (see De Lazari-Radek and Singer 2014 : 162–3). Given his substantive claims about the relative strength of personal and impartial reasons, he is best read as a weak moral rationalist, holding that morally required action is always rationally permissible , but not always rationally required .

Joseph Raz favors the thesis of widespread incommensurability of reasons as the best explanation of the truth of the basic belief ( Raz 1999 : 102). This thesis is in many ways similar to Parfit’s thesis of imperfect comparability, since both theses directly account for that fact that, of two reasons, neither need be stronger than the other, even when they are not precisely equal in strength. Raz also shares Parfit’s view that certain substantive facts—such as the fact that a certain book is good, or the fact that one has promised to call one’s mother—can provide reasons for doing things, such as reading the book, or making the phone call. But Raz also holds that “the primary significance of reasons [ . . . ] is to make certain responses eligible” ( Raz 2012 : 5; see also Raz 2012 : 133 and Raz 1999 : 65, 98–101). The eligibility of one action is compatible with the eligibility many other incompatible actions. It is true that one set of reasons can, sometimes, rule out acting on another set. This is what Raz means when he says that one set of reasons defeats another. But he also holds that it is generally false that one of the available options is supported by reasons sufficiently strong to defeat all others ( Raz 1999 : 100). Now, when two opposed reasons (or sets of reasons) are incommensurate, neither defeats the other (p. 103). This explains why reasons generally fail to determine a unique choice.

Raz’s view gives rise to a generalized form of Parfit’s “rationalist’s problem”: reason cannot help us decide between options when those options are favored by incommensurable reasons. Raz’s response to this problem is largely to concede it, but to deny that is really a problem (1999: 117). He stresses that each of us has what we might call a “motivational profile” that is the source of our particular willings, and also of the attitudes with which we perform the actions that we choose to perform—eagerly, reluctantly, with disgust or guilt, and so on. When confronted with a range of options, each of which is made eligible by the relevant reasons, we do not typically find ourselves paralyzed with indecision. Indeed, those who know us can often predict how we will act. The fact that an unchosen option was favored by an undefeated reason does not undermine the fact that the option we did choose was itself favored by undefeated reason ( Raz 1999 : 65–6, 109–11), so that it can be said that we acted for a reason , and that we acted rationally (see Raz 1999 : 47). Underdetermination by reason would be a problem if it generally left us in the lurch, like Buridan’s ass. But we are not left in the lurch under such circumstances, since there is more to us than pure reason.

19.2 Parity

Ruth Chang’s explanation of underdetermination by reason depends on the existence of a fourth positive value relation, which she calls “parity” ( Chang 2002 ). The traditional positive value relations are “better than,” “worse than,” and “equally good.” An account of parity is not in itself an account of practical reasons or of their strength, so it is also obviously not an account of how it is that reasons can underdetermine choice. But it is very plausible that the claim that choice A is better than choice B is at least materially equivalent to the claim that the relevant reasons that favor A are stronger than the relevant reasons that favor B. So if one holds that any pair of options are related by one of the three traditional positive value relations, it would be quite natural to think that this entails the following: that the reasons that favor one option will always be stronger than, weaker than, or of equal strength to the reasons that favor another. By adding parity to the traditional three positive value relations, Chang can therefore explain how it is that the reasons that favor one option might be neither stronger than, weaker than, nor of equal strength to the reasons that favor another. This opens up the same sort of space for Raz’s basic belief that is provided by widespread incommensurability, as long as we regard a choice as rationally eligible whenever there is no rival option favored by stronger reasons. And this is good news for those who want to embrace the basic belief, but who doubt that incommensurability is sufficiently widespread to provide an adequate explanation.

A standard sort of example used to illustrate parity might involve a choice between two quite different vacations, or two quite different jobs. One can often be quite clear than neither member of such a pair is better than the other. Put in terms of reasons, one can often be quite clear that neither member is favored by stronger reasons. Admittedly, this same claim is also true when each option is favored by reasons of precisely equal strength. But it is also often clear that if the price of one of the vacations went down by a few hundred dollars, or if the salary of one of the jobs went up by a few thousand, the initial evaluative claims would remain true: neither option would be better than the other. This seems to rule out the idea that the two options had initially had precisely the same value. Such cases—which Chang calls “hard cases”—are part of what motivate the recognition of a fourth value relation. Of course there are other interpretations of what is going on in hard cases. One obvious one is that they are cases of incommensurability. But the fact that a sufficient improvement in one of the vacations or one of the jobs would decide the matter at least suggests that the initial relation wasn’t incommensurability. Another interpretation of hard cases is that they are nothing more than mundane case of vagueness in one of the traditional three value relations. And there is an epistemic interpretation as well: that although one of the three value relations does in fact characterize the case, we lack sufficient insight to determine which one it is. Chang argues against each of these alternate interpretations, but there is no need to go into her arguments here.

If Chang is right about parity, then she can explain how it is that reasons can “run out” as often as they seem to do. All she has to do is to say that when one has reasons that favor one choice, and those reasons are not weaker than those that favor any alternative choice, then we have sufficient reason to opt for that choice. If parity often characterizes the relations between a number of our eligible options, then we will equally often find ourselves in situations in which we have sufficient reasons for many different options; reasons will have failed to determine our choice. Although in many ways this is a desirable result—it is an explanation of the truth of Raz’s basic belief—Chang is more aware than many theorists of the problems it presents, both practically and theoretically. One of these begins with what Parfit called “the rationalist’s problem.” As Chang puts it, the problem is that in such situations, it seems that all we can do is “pick or plump for no reason” ( Chang 2009 : 249). As we’ve seen, Raz’s response to such a situation is not to worry about it. He simply accepts that since we are more than creatures of pure reason, there is nothing wrong with choosing as we feel like choosing—even though “feeling like it” is not itself a reason. One of Chang’s motivations for trying to say something more than this is that in cases in which reasons have run out, we do not always simply “pick or plump.” Rather, we often continue to deliberate. So there is a further problem here that Raz seems to have failed to consider: how is it that such deliberation can be reasonable, given our certainty that there are no further reasons to consider? Chang seems to think that the reasonableness of further deliberation shows that what we are after is a choice that is determined by reason—one that is favored by most reason ( Chang 2009 : 254).

Chang’s explanation of the reasonableness of our continued deliberation when reasons have run out is to distinguish between two sorts of reasons: given reasons, which do not depend on our wills, but may stem from facts about normative reality, and voluntarist reasons, which do depend on our wills, and which come into play after the given reasons have run out. Voluntarist reasons result from our taking something to be a reason, which might not have been a reason before one took it to be so. Since taking something to be a reason is itself something we do , we have an explanation of the appropriateness of deliberating about our choice even after we’ve assured ourselves that the relevant given reasons do not determine what we should do. The further deliberation is about which considerations we will turn into voluntarist reasons, which may then affect the balance of reasons so that one choice emerges as the uniquely rationally favored one. Sometimes, of course, even this further deliberation will fail to yield a voluntarist reason of sufficient strength to determine choice uniquely, and in that case Chang holds that one can only pick or plump for no reason ( Chang 2009 : 265, n. 26). But of course sometimes we do simply pick or plump, so this is no objection.

One worry about Chang’s view is that, if it is understood in such a way that it accommodates Raz’s basic belief, then it seems merely to relocate the arbitrariness that results from underdetermination by reasons, rather than removing it. In particular, it helps to eliminate arbitrariness from our determination about what to do based on the given reasons, but that arbitrariness reappears in the context of deliberation about what voluntarist reasons to create. To see this, note first that if the creation of voluntarist reasons were itself guided by given reasons and were always rationally determined, then we would be left without the rational latitude central to the basic belief. But Chang denies that the creation of voluntarist reasons is itself reason-guided ( Chang 2013 : 184–5). Rather, it is just something we do . But then it looks as if our choices, when they are the result of voluntarist reasons, are arbitrary: we simply create certain voluntarist reasons spontaneously—not as the result of guidance by reasons—and these voluntarist reasons then (in many cases) determine our choice of action.

Chang’s response to the above worry seems to be to admit that there is some arbitrariness in our creation of voluntarist reasons, but to hold that it is not objectionable. Why? Because there are substantial boundaries set by our given reasons, and these boundaries prevent our voluntarist reasons from being able to make it the case that we have most reason to—for example—go on a killing spree, or cut our feet off. As she puts it, “We can create voluntarist reasons only in the space of rational freedom afforded by our given reasons” ( Chang 2009 : 269). But the worry about widespread arbitrariness in our decisions is distinct from a further worry that such arbitrariness will allow for wildly unreasonable choices. Chang’s response here seems only to address the second of these worries. So it is doubtful that she will have reassured those who have the “mere arbitrariness” worry. Whether anyone should worry about mere arbitrariness is another matter. Clearly Raz is not worried. And, as we will see, neither is Douglas Portmore.

A second worry about Chang’s view is that one of her central assertions calls out for an explanation: that voluntarist reasons can only determine choice within the boundaries provided by given reasons ( Chang 2013 : 179). If we can genuinely create reasons by an act of will, why is it that these reasons can never, by any stretch, tip the balance of reasons in such a way that an option that had formerly been ineligible becomes eligible? It is easy to see why Chang would want this to be true: otherwise she cannot deflect the “unreasonable arbitrariness” worry (pp. 183–4). But it is harder to see why we should take it to be true. Chang asserts: “Metaphysically speaking, if we have the freedom to create reasons, we have it only within the confines of the reasons we have no freedom to create, our given reasons” (p. 179). But this is not an argument; it is the point to be established. She does make an analogy with our non-normative powers, pointing out that we are constrained by the non-normative facts given to us. But this analogy does not serve her well; after all, we can change the non-normative facts that are given to us. Suppose we are being swept out to sea by a strong current. If we consider only the given forces acting on us, we can predict that we will end up at one of a number of distinct points: all of them out at sea. But if we exercise our non-normative powers and swim across the current in one direction or other, we can change this range of points so that some of them are along the shore.

Another feature of Chang’s view that is worth drawing attention to is that the considerations that we will to be reasons must already count in favor of the option, even though they are not yet reasons. That is, one cannot simply will anything to be a reason ( Chang 2013 : 180, n. 32). But if a consideration already counts in favor of an action, it is hard not to think that it already is a reason, even without our willing it to be one. So the willing one does, with respect to this consideration, might better be regarded as something other than willing it to be a reason. Perhaps it might simply be willing to be influenced by it. This way of viewing matters makes some reasons optional in a certain way, but does not make their very status as reasons optional. The optionality of such reasons might be explained in terms of their being the sort of reasons that can rationally justify our choices, should we choose to act on them, though they cannot rationally require them, since we need not be influenced by them. This distinction—between justification and requirement—is explored at greater length in section 19.4 .

19.3 The Ubiquity of Ties

A third method for explaining the rational underdetermination of choice by reason is due to Douglas Portmore (see Portmore 2011 , 2013 ). Suppose that reasons come with single precise strength values, contrary to views so far discussed. Even if this were true, we might still often find ourselves with a large number of equally eligible options. To see this, suppose, to begin with, that the uniquely favored option in a certain situation is to grade a stack of student papers. Still, given that there are—alas!—thirty-five papers, there are literally billions of ways in which one might go about this task, even considering nothing but the order in which one grades the paper. That is, it would be rationally permissible, right now, to pick up Eric Fleming’s paper and begin to grade it, but it would also be rationally permissible to pick up Michael Katz’s paper and grade it, or Alejandro Donnantuoni’s. All of these choices are parts of ways of doing what one has most reason to do: grading all the papers. As a result, the available reasons seem to favor each of them to the same degree. And since there are typically many ways of performing actions, this kind of situation seems very likely to be a common one. As a result, it looks as if we will have many rationally permissible options, even if we embrace the thesis that reasons come with single precise strength values.

The brief argument offered above may not seem to accomplish very much. The kind of rational latitude that stands behind Raz’s basic belief should not—one might think—be modeled on the latitude we have to pick which paper to begin grading. Rather, when Raz puts forward the basic belief, he is thinking of the choice to have another child or not, or to go to graduate school rather than staying in industry making a lot of money. Against this, however, Portmore suggests that the same style of argument used to show that we often have what might be called “trivial latitude” can also be used to show that we also have, and equally often, what might be called “significant latitude.”

To begin to see how Portmore’s position might be plausible, consider that grading all thirty-five of one’s papers is a task that will occupy some time, and that grading Eric Fleming’s paper is a subtask that will occupy a part of it. It is because of this part–whole relation between grading Eric Fleming’s paper and grading all of the paper that we have the rational option, right now, of grading his paper, or of grading Michael Katz’s, or Alejandro Donnantuoni’s. The relative triviality of the choice here stems fairly directly from the relative smallness of the task of grading the papers. But what if the larger activity were not simply grading all of one’s papers, but living a worthwhile life? Surely there are many ways of living a worthwhile life, and many smaller activities that make up those ways. If what we have most reason to do is to lead a worthwhile life, why not say that, as long as what I choose to do now is part of doing that , then I am acting as the balance of reasons requires me to do? If this is all correct, then it may be that, right now, I would be acting in a rationally permissible way if I went to the movies, but also if I decided to volunteer my time at a local shelter, or if I quit my academic job in order to begin studying to be a nurse. All of these activities, whether altruistic or self-interested, could certainly be part of my living a worthwhile life.

One initial objection to Portmore’s view is that it seems to have the consequence that I have just as much reason, now, to go to the movies as I have to volunteer at the local shelter, or to quit my academic job and begin studying to be a nurse, at least on the assumption that I could live an equally valuable life whichever option I chose. But it seems as if these options are obviously favored by different reasons, and may therefore have different rational statuses. Indeed, it seems as if I could not possibly have just as much reason to go to the movies right now as I have to volunteer at the local shelter. After all, if I go to the shelter, this will—let us grant—have some significant good consequences for a number of the patrons of the shelter, while if I go to the movies, the only benefit will be a relatively trivial one, for me. Against all this, Portmore argues that it is a mistake to try to determine the rational status of an action outside of the context of the larger set of actions of which it is a part ( Portmore 2013 : 437). Although this is a surprising result, it is the natural consequence of a certain way of looking at the following sort of case, which we can call the “two treatment case.”

Suppose that an agent, Joseph, has just learned that he is suffering from an illness that will permanently disable him if not treated within the week, but which—luckily—can be treated in two equally effective ways: A or B. Upon learning about his illness, Joseph immediately makes an appointment with one doctor on Monday to receive treatment A, and another appointment with another doctor on Friday to receive treatment B. He makes both of these appointments in the belief that two treatments are better than one. But he then learns that while each treatment is safe and fully effective on its own, the combination of both is worse than useless: it is significantly harmful. What should Joseph do? It seems that the following are both true:

It is rationally permissible for Joseph to get treatment A on Monday.

It is rationally permissible for Joseph to get treatment B on Friday.

But, perhaps surprisingly, we cannot “combine” (1) and (2) to get the following:

It is rationally permissible for Joseph to get treatment A on Monday and to get treatment B on Friday.

Portmore’s interim suggestion for dealing with this case is that we should focus on the rational permissibility of Joseph’s options for the whole week , and we should evaluate the rational status of his behavior during smaller intervals in that week in terms of the existence of a rational plan for the whole week that includes that “short interval” behavior. That is, we should note that the following are both true about Joseph’s behavior over the week:

It is rationally permissible for Joseph to get treatment A on Monday and not get treatment B on Friday.

It is rationally permissible for Joseph to not get treatment A on Monday, and get treatment B on Friday.

Since (4) includes Joseph’s getting treatment A on Monday, we have an explanation of the truth of (1). And since (5) includes Joseph’s getting treatment B on Friday, we have an explanation of the truth of (2). But since neither (4) nor (5) (nor any other rationally permissible way of acting during the week) includes Joseph’s getting both treatments, we do not have to accept (3). Indeed, since no rationally permissible plan for the week includes both treatments, we can conclude that (3) is false. These are all good results, and may seem hard to obtain on some other accounts.

The rationale for expanding our view to include the whole week, rather than each day, obviously continues to apply as we expand our view from the week to the month, to the year, and beyond. Indeed, there is no principled stopping-point short of the end of the agent’s life as an agent. And this is in fact where Portmore draws his line. That is, the options that he assesses directly for rational permissibility are maximal options: maximally specific sequences of actions that extend from the present to the time at which the agent ceases to be an agent any longer ( Portmore 2013 : 442). A non-maximal option (such as going to sleep right now, or making a sandwich, or calling one’s mother) counts as rationally permissible if and only if it is part of one of one’s rationally permissible maximal options.

How is it that Portmore addresses the problem of rational arbitrariness that comes along with any view that accounts for Raz’s basic belief? One response he could offer is to claim that it simply is not a problem that needs solving, given his explanation of underdetermination. His explanation is, in essence, to say that many options are tied for first place, so that there is nothing wrong in its being true that our choice of one of the options over the other is indeed arbitrary. It might not seem that my watching some television right now and my volunteering at a shelter right now are both equally supported by reasons, but that is just one of many instances of appearances being deceptive. Given that if I volunteer now I can watch some television later, and that if I watch some television now I can still volunteer later, and given that both activities form part of an optimal maximal option, there is as little to choose between them as there is to choose between beginning my grading with Eric Fleming’s paper or with Michael Katz’s paper.

It is not clear how satisfactory the above response is. The phenomenology of picking between seven identical boxes of cereal, or randomly selecting which paper, in a stack of thirty-five, to begin grading, is quite different from the phenomenology of other choices between rationally permissible actions (see Holton 2006 ). Indeed, the distinction between picking and choosing seems to exist partly because of this difference: picking is what one does when one’s options seem to be indistinguishable in terms of what matters, while choosing is what one does when one pays attention to certain reasons that favor the different options and forms a preference on that basis (see Ullman-Margalit and Morgenbesser 1977 ). Moreover, Portmore’s explanation of Raz’s basic belief makes almost every one of our choices—even ones we do not regard this way—into a choice between innumerable options that are equally well-supported by reason.

One way that Portmore could try to capture the phenomenology of choosing, as distinct from picking, would be to analogize the choice between optimal maximal options to the choice between, say, houses, rather than the choice between identical boxes of cereal or between various different orders in which one could grade a stack of papers. When one chooses a house, what one is looking for is a balance between neighborhood, price, distance from work, coziness, convenience, charm, and so on. Even on the assumption that each of these considerations provides a reason with a univocal sort of strength and that one can just “add them up,” it is easy enough to imagine that several very different houses might end up being tied for first place. The choice of one of these houses might be rationally arbitrary in the sense that each of them is favored equally in a calculus of the desirable and undesirable features. But there is no problem in imagining someone deliberating about which one to choose, and being unsatisfied with the idea of simply rolling some dice in order to come to a decision. It is true that there is something odd—not to say wrong—about being the sort of person who tends to pick the leftmost cereal box, or the sort of person who grades papers in alphabetical order. But there is nothing odd in being the sort of person who is most influenced, in choosing a house, by facts about proximity to work, and who is least influenced by facts about price. Deliberation might be the process of trying to get all of the relevant factors into view, so that one is well-satisfied with the balance of considerations—though rationally speaking, there is no difference between one’s preferred balance and other balances (compare Sen 2004 : 44). Note, however, that being well-satisfied here is not—and cannot be—a further reason for Portmore, since this would break the tie that gives rise to the agent’s options.

19.4 The Justifying/Requiring Distinction

In trying to give some theoretical basis for a significant underdetermination of choice by practical reasons, some of the theorists I’ve so far discussed deny that we should take the notion of the strength or weight of a reason too literally. If we took it literally, we would have to hold that any given reason had a determinate strength value. And if this were true, we could just add up these values as they favor and oppose our available options, and this would determine which act was best supported by reasons. It is certainly true that by refusing to treat the strengths of reasons as related in anything like the way that real numbers are related, Raz, Parfit, and Chang avoid having to say that reasons typically determine choice uniquely. But another strategy is to shift the focus away from the issue of how literally we should take talk of weight or strength, and turn that focus instead onto the assumption that the normative capacities of practical reasons should be thought of as being characterizable by means of a single strength value ( Gert 2004 : chs 2, 4, and 5). Recognizing two dimensions of normative strength also allows us to avoid the implausible implications of Portmore’s strategy for explaining the ubiquity of rational options. Portmore’s strategy, recall, posits a ubiquity of perfect ties in support by reasons, even among actions that seem, at an intuitive level, to be favored by quite different reasons, with quite different normative capacities.

The strategy of recognizing more than one dimension of normative strength makes underdetermination by reasons formally parallel to the underdetermination characteristic of commonsense morality described at the very beginning of this chapter. Commonsense morality gives us a great deal of moral latitude by being primarily a system of prima facie prohibitions (that is, prima facie requirements not to do something), along with potential justifications for violating those prima facie prohibitions. Some moral considerations, such as those of self-defense, only have the power to justify. Others—such as the fact that it is one’s legal duty to administer punishment—can both justify and require. Any action that is not subject to a prima facie prohibition is among our moral options—as are many actions that violate such a prohibition, as long as there is sufficient justification for doing so. This same structure—the existence of (a) reasons that give rise to prima facie requirements and (b) reasons that can justify acting in the face of those prima facie requirements—can easily be seen as applying to the domain of rationality. And the normative results are quite plausible. For example, the prima facie prohibitions of rationality might include killing oneself, hurting oneself, disabling oneself, and so on, while the justifications might include saving someone’s life (one’s own, or that of some other person), preventing someone from suffering pain, preventing someone from being disabled, and so on. Some of these justifications might be analogous to considerations of self-defense in morality: mere justifications, lacking the power to generate rational requirements.

The formal parallel between the structure of morality and the structure of rationality yields two distinct forms of strength for any given practical reason. Since a prohibition on Φ-ing is just a requirement to not-Φ, and a requirement to Φ is just a prohibition on not-Φ-ing, we can put all talk of prohibitions in terms of requirements. Having done this, we can see that justification and requirement (and therefore justification and prohibition) are two distinct dimensions of strength by considering the following two questions, which one might ask about any given reason:

(R) How much can this reason require me to do? (J) How much can this reason justify me in doing?

Since these are “How much” questions, the answers will be something like amounts .

Typically any non-trivial reason can justify more than it can require. To see this, consider a self-interested reason, such as the reason you have to avoid suffering a fierce itch that will last a couple of days. Let us call this reason “S.” And consider a quick treatment that will prevent the itch completely, but that will cause you a certain amount of short-term pain. Finally, ask yourself what the maximum amount of that short-term pain is that you would take yourself to be rationally justified in suffering, in order to avoid the fierce itch. Your answer to this is an answer to the question (J), given in the currency of pain. Call this answer “P J .” P J is a measure of the justifying strength of S; it is how much S can justify. Now, whatever value you take P J to be, surely it does not follow that the same value is appropriate in response to the question (R), asked about that same reason S. In fact, it is exceedingly plausible one could be rationally required only to suffer something less than P J . Put another way, one is not required to suffer the maximum that one would be justified in suffering. Call your answer to question (R), again given in the currency of pain, “P R .” P R is a measure of the requiring strength of S; it is how much S can require. The upshot here is that J R is greater than P R ; the justifying strength of S is greater than its requiring strength.

Now consider an altruistic reason, A, such as the reason you have to help an unpleasant student prepare for an exam when he arrives in the last minutes of your office hours. How much time would you be justified in spending helping this student? Well, even if you had no special connection with the student, you would—it is plausible to hold—be rationally justified in staying quite late; there would be nothing irrational in this sacrifice. However long you think it would be rationally permissible to stay is your answer to the question (J), given in the currency of time spent teaching an unpleasant person. Call this answer T J . T J is a measure of the justifying strength of A. But, again, whatever value you take T J to be, surely it does not follow that the same value is appropriate in response to (R), asked about reason A. Indeed, if you do not have any special obligation to stay and help the student, I would say that the altruistic reason does not rationally require that you spend any time helping him study. That is, it is not irrational to tell this student that your office hours have just ended, and advise him to come earlier next time. I think this is typical of altruistic reasons; they can justify far more than they can require. In any case—whether the answer to (R) in this case is “nothing” or “very little”—call that answer “T R .” T R is a measure of the requiring strength of A. The upshot here is that the justifying strength of A is greater—probably far greater—than its requiring strength.

If there is typically a non-trivial gap between the justifying and requiring strengths of any given practical reason, then we have a ready explanation of Raz’s basic belief. That is because, on this view, being rationally permissible is not a matter of being favored by reasons to a degree that is at least as great as any other option. Rather—in a way that is formally similar to the structure of commonsense morality—being rationally permissible is a matter of being favored by reasons that are sufficient to justify acting against whatever opposed reasons there happen to be. To take a schematic example, suppose that one is faced with a choice between suffering a certain amount of pain or relieving a somewhat greater amount of pain for a stranger. Old-style hedonistic act-utilitarian views, reinterpreted as views of rationality, might (implausibly) purport to yield a uniquely correct answer in this case. But common sense, and all the philosophers considered in this chapter, reject this conclusion. Rather, if one wishes to make the sacrifice for the stranger, this is rationally permissible. And if one does not wish to do so, that also is rationally permissible. By recognizing the distinction between the requiring and justifying strengths of reasons, both of these facts are easily explicable. The reason that favors relieving the stranger’s pain has sufficient justifying strength to make it rationally permissible to suffer a somewhat smaller pain oneself. But since that altruistic reason does not have any—or very much—requiring strength, the reason to relieve one’s own pain has (more than) sufficient justifying strength to make it rationally permissible to refuse to make the sacrifice for the sake of the stranger.

A plausible assignment of justifying and requiring strengths to self-interested and altruistic reasons yields the sort of rational assessments of action that are in line with our everyday assessments. In particular, it yields the following: that the only irrational actions are those that involve some harm to the agent without bringing some compensating benefit to someone—whether that “someone” is the agent or another person. This allows selfless sacrifice to count as rationally permissible (up to a point), but it also allows a degree of preference for oneself, including a degree that many might regard as quite selfish. It also allows much immoral action to count as rationally permissible, eliminating worries that stem from too tight a connection between rationality and morality. One of these worries is of course simple prima facie implausibility. Much immoral action, when the benefits are great and the risks are low, certainly does not seem to be irrational in the fundamental objective sense of “irrational.” This fundamental sense is that one that disallows a “So what?” response to the knowledge that one’s action is irrational (see Darwall 1983 : 215–16; Nagel 1970 : 1–9; Gibbard 1990 : 49). Another worry stems from the fact that significant irrationality tends to undermine responsibility. It is true that the most relevant form of irrationality here is subjective irrationality, which is not directly determined by reasons, but includes such defects as akrasia. But if one knowingly performs an act that is irrational in the objective sense, this also counts as subjectively irrational. As a result, if objective rationality and morality are too tightly linked, it will be difficult to explain why it is appropriate to hold people responsible for egregiously immoral behavior. And it will be especially difficult if the immoral behavior stems from a stable state of character, since then the very source of the action will involve the agent’s being irrational in a certain respect.

Because the distinction between the justifying and requiring strengths of reasons opens up such a large space of rationally eligible choices, it also raises the worries we’ve seen above, both about arbitrariness and about the fact that we often continue to deliberate even after it is clear that the relevant reasons do not determine what we ought to do. Both of these worries can be dealt with by stressing a distinction briefly mentioned above, between objective rationality and subjective rationality. Objective rationality is determined by the facts that constitute the reasons for and against our various options. It is objective rationality we are concerned with when we are trying to find out the facts of relevance to our choices. If, through no fault of our own, we fail to discover some of these facts, our action may be objectively irrational, but that is no reflection on our rational capacities. Subjective rationality, on the other hand, has a more intimate tie to proper mental functioning and such associated phenomena as moral responsibility, competence, and mental illness. Many philosophers acknowledge a distinction between objective and subjective rationality, but they nevertheless understand the two concepts as strongly analogous . That is, for example, they hold that objective rationality is a function of the reasons there are , while subjective rationality is a function of the reasons the agent takes there to be (see Brandt 1979 : 72–3; Gibbard 1990 : 18–19; Harman 1982 : 127; Raz 1999 : 22; Parfit 2011 : 36). This strategy will not help at all in addressing the worry about arbitrariness, since the same kind of latitude will appear in both subjective and objective rationality, in virtue of their isomorphic structure.

Happily, there is another conception of subjective rationality available: a reliabilist one. On such a conception, for an action to be subjectively irrational is for it to stem from a mental state that puts the agent at increased risk (relative to normal agents) of performing objectively irrational actions. Any action that is not subjectively irrational is subjectively rational. On this conception of subjective rationality, the kinds of desires and commitments to which Raz appeals as causing us to act in a rationally acceptable but also rationally arbitrary way are in fact relevant to what will count as (subjectively) rationally eligible. What the reliabilist account allows is that these desires and commitments can be relevant to subjective rationality without themselves counting as reasons (see Gert 2009 ). How is this possible? Suppose that one’s objectively rationally eligible options are A, B, and C. And suppose that one has an overall preference to for B, rather than for A or C. If one nevertheless chooses A or C, what could account for this? Well, perhaps an unreasoning fear, or a pathological concern for what seems cool, or just the “imp of the perverse.” Who knows? But some such explanation will have to be true, if one’s overall preference, in light of one’s plans, commitments, and so on, is for B. And if this is correct, then one’s action will count as subjectively irrational, despite being objectively rational.

It is true that the above account of subjective rationality is subject to a concern that is analogous to a standard objection to reliabilist accounts of knowledge: the generality problem. This is the problem of identifying the relevant state, in order to determine whether it places the agent at increased risk of performing objectively irrational actions. To make the problem vivid, consider that even a perfectly reasonable—but false—belief may well put one at increased risk of performing objectively irrational actions. But we do not want to count such action as subjectively irrational. In this case, the reliabilist about subjective rationality will want to say that it is the prior states—the ones that led to the (perfectly reasonable) false belief—that are relevant, and that these states do not put the agent at increased risk. The question is whether the reliabilist can provide any principled way of defending this choice. Let us put this worry aside, however, since it is common to all reliabilist accounts of anything, and since rival accounts of subjective rationality have problems that seem at least as significant ( Gert 2004 : ch. 7).

If one adopts the reliabilist account of subjective rationality, one’s commitments, plans, desires, and so on, despite not themselves counting as reasons, can narrow one’s (subjectively) rational options down quite considerably. This so significantly reduces the scope of rational arbitrariness as to constitute a solution to the associated problem. And because it solves the problem without introducing a second sort of reason , we do not run into the problem Chang had, which was the need to stipulate , without argument, that the reasons that come in to reduce arbitrariness (Chang’s voluntarist reasons) cannot themselves make something rationally eligible that had been ruled out by the objective (given) reasons. Because desires and commitments are relevant to rationality without themselves being reasons, we also avoid the problem Chang faced of having to limit potential voluntarist reasons to considerations that already favor and disfavor options, and which therefore already seem to be reasons.

What about the second problem Chang raised: the fact that it is quite common to continue to deliberate even after it is clear that one’s reasons do not determine what one should do? One solution—suggested by the reliabilist account of subjective rationality, but by no means tied to it—is to reject the assumption that deliberation is typically an explicitly normative endeavor: a determination of which of our options is best supported by reasons. Rather, a more modest and realistic view of deliberation is simply that it is a reliable technique for surveying the available options, focusing on the most relevant considerations, and coming to a decision. An agent can make use of this technique without making any sort of normative judgment that the decision she ultimately lights on is better than the options she rejected. Philosophers who are used to thinking of human beings as rational agents might balk at this description, suggesting that human action is the product of our distinctive rational capacities, which involve normative assessments of the reasons that favor and oppose action. But this wildly misdescribes our mental lives. Typically we do not deliberate at all about what we are going to do. Rather, a salient option often appears to us for the very first time as the content of a spontaneous intention: it’s time to go to class, so we go; we’re running out of gas, so we stop at the station. It is true that in other cases there are obviously many eligible options, and none of them strikes us as the obvious or most attractive choice. In such cases, we sometimes deliberate. But even then, there is no need to take deliberation to be a search for an answer to the normative question “What do the reasons best support?” Rather, when we are at a loss for an immediate choice, deliberation often takes the simple form of thinking about what it would be like to pursue each of the options, and what the longer-term consequences might be. In light of this reflection, we spontaneously form an intention, and act. If we view practical deliberation more on the model of a survey of the options , which need not make use of any normative concepts, then Chang’s second problem disappears.

One worry about the strategy presented in this section is that it relies on a mysterious notion of normative strength. But even those who express worries about the notion of the weight of a reason seem happy to take such talk as acceptable when it is interpreted merely as a way of talking about, and quantifying, the relations between reasons. For example, Daniel Star and Stephen Kearns are explicit in their worry about the notion of the strength of a reason, but do not object to T. M. Scanlon’s “top-down” approach ( Kearns and Star 2015 : 238, n. 10). Here is what Scanlon says:

there is no non-normative coin or normative coin, in terms of which the strength of reasons, considered on their own apart from comparison with other particular reasons, can be expressed, and which then serves as a basis for comparative judgments of the kind involved in [claims that a certain reason is sufficient to justify, or to require, an act in a given set of circumstances]. The strength of a reason is an essentially comparative notion, understood only in relation to other particular reasons. ( Scanlon 2014 : 111)

This view is classified as “top-down” because it relies on the idea that basic normative judgments are “high-level”; they concern a reason being—overall—sufficient or conclusive. Claims about sufficiency or conclusiveness are not about pro tanto reasons or their strengths. Rather, they express the idea that a given action, favored by a given reason, is—overall—rationally justified, or rationally required. Given judgments of this “high-level” kind, Scanlon holds that we can understand the comparative claim that reason A is stronger (say, in the justifying role) than reason B as the claim that reason A would be sufficient in a certain circumstance, but that reason B would not be sufficient in A’s place. It is true that the first part of the quotation from Scanlon seems to express some sort of skepticism about taking talk of the strength of reasons too seriously; Kearns and Star take it to show that Scanlon “rejects the view that weights are real, independent properties of reasons” ( Kearns and Star 2015 : 238, n. 10). But someone who agrees with Scanlon can certainly accept the justifying/requiring distinction precisely as I have presented it in this section; my definitions of comparative facts about the justifying and requiring strengths of reasons are paradigmatically “top-down” (see Gert 2004 : 66–8).

It may be worth mentioning here that the top-down approach seems appropriate even for straightforwardly non-normative properties. For example, the charge of a particle must be understood in terms of the force it produces in another charged particle. It is true that physical force itself is directly expressible in the “coin” of acceleration and mass. But electromagnetic charge , as opposed to electromagnetic force , is another matter; we can determine the force exerted on an object without knowing its charge, but we cannot determine its charge without reference to other charged objects. So the assignment of justifying and requiring strengths to normative reasons seems as unproblematic as the assignment of electromagnetic charges. 1

19.5 Concluding Remarks

One notable feature of all of the theorists discussed in this chapter is that they hold that reasons are provided by facts about objective values. Even Chang, who makes use of the notion of a voluntarist reason, requires that the facts that one wills to be reasons already have the sort of value that allows them to be willed to be reasons. It is somewhat surprising that objectivism should go hand-in-hand with the idea that reasons—and the values that give rise to them—do not determine how we ought, rationally, to act. After all, objectivity seems intuitively to be associated with determinacy. Perhaps equally surprisingly, the converse of the link between objectivity and rational underdetermination also seems to hold. That is, if one takes reasons to be subjectively determined by one’s contingent desires, it then turns out to be natural—not to say obligatory—to say that we have fewer rational options than the objectivist countenances. Why? Because it is more plausible that one’s desires are characterizable in terms of a single, commensurable sort of strength than it is that objective values are. And if one’s desires are characterizable in this way, and if one’s reasons are a function of these desires, then it is a natural consequence that one’s reasons also will have unique and commensurable strength values. To the degree, then, that one thinks that we do in fact have a great deal of rational latitude in our everyday choices, one has reason to reject subjective, desire-based theories of reasons, and to accept a more objective, desire-independent view.

Brandt, R. ( 1979 ). A Theory of the Good and the Right . Oxford: Oxford University Press.

Google Scholar

Google Preview

Chang, R. ( 2002 ). “ The Possibility of Parity. ” Ethics 112: 659–88.

Chang, R. ( 2009 ). “Voluntarist Reasons and the Sources Of Normativity.” In D. Sobel and S. Wall (eds), Practical Reason and Action , 243–71. Cambridge: Cambridge University Press.

Chang, R. ( 2013 ). “ Grounding Practical Normativity: Going Hybrid. ” Philosophical Studies 164: 163–87.

Darwall, S. ( 1983 ). Impartial Reason . Ithaca, NY: Cornell University Press.

De Lazari-Radek, K. , and P. Singer ( 2014 ). The Point of View of the Universe: Sidgwick and Contemporary Ethics . Oxford: Oxford University Press.

Gert, J. ( 2004 ). Brute Rationality: Normativity and Human Action . Cambridge: Cambridge University Press.

Gert, J. ( 2009 ). “ Desires, Reasons, and Rationality. ” American Philosophical Quarterly 46: 319–32.

Gibbard, A. ( 1990 ). Wise Choices, Apt Feelings . Cambridge, Mass.: Harvard University Press.

Harman, G. ( 1982 ). “Review of A Theory of the Good and the Right by Richard Brandt.” Philosophical Studies 42: 119–39.

Holton, R. ( 2006 ). “ The Act of Choice. ” Philosophers’ Imprint 6: 1–15.

Kearns, S. , and D. Star ( 2015 ). “Weighing Explanations.” In I. Hirose and A. Reisner (eds), Weighing and Reasoning: A Festschrift for John Broome . Oxford: Oxford University Press.

Nagel, T. ( 1970 ). The Possibility of Altruism . Princeton, NJ: Princeton University Press.

Parfit, D. ( 2011 ). On What Matters , vol. 1. Oxford: Oxford University Press.

Portmore, D. ( 2011 ). Commonsense Consequentialism: Wherein Morality Meets Rationality . New York: Oxford University Press.

Portmore, D. ( 2013 ). “ Perform your Best Option. ” Journal of Philosophy 110: 436–59.

Raz, J. ( 1999 ). Engaging Reason . New York: Oxford University Press.

Raz, J. ( 2012 ). From Normativity to Responsibility . New York: Oxford University Press.

Scanlon, T. M. ( 2014 ). Being Realistic about Reasons . New York: Oxford University Press.

Sen, A. ( 2004 ). “ Incompleteness and Reasoned Choice. ” Synthese 140: 43–59.

Setiya, K. ( 2011 ). Review of On What Matters , vols 1 and 2. Mind 120: 1281–8.

Ullman-Margalit, E. , and S. Morgenbesser ( 1977 ). “ Picking and Choosing. ” Social Research 44: 757–85.

Thanks to John Roberts for this example.

For comments on an earlier version of this chapter, thanks to Victoria Costa, Daniel Star, and Garrett Cullity.

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Underdetermination

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The underdetermination thesis states that any given realm of phenomena can be captured by a variety of empirically equivalent accounts. The evidence leaves room for more than one theoretical description and explanation. The underdetermination thesis presupposes a distinction between an observational level and a theoretical level and assumes a conceptual distance between the two. The claim is, then, that logic and experience alone are insufficient for singling out a privileged account of the phenomena. The relevant theoretical alternatives may differ locally or globally, their empirical equivalence may be permanent or transient, they may exist universally or contingently, and they may be genuinely distinct or depend conceptually on one another. The underdetermination thesis is contentious; critics consider it false or trivially true, depending on the version entertained.

The rise of the underdetermination thesis is in large measure the result of the methodological...

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Carrier M (2011) Underdetermination as an epistemological test tube: expounding hidden values of the scientific community. In: Schurz G, Votsis, I (eds) Scientific realism Quo Vadis? Theories, structures, underdetermination and reference. Synthese 180:189–204

Google Scholar  

Duhem P (1906) The aim and structure of physical theory. Atheneum, New York, 1974

Gillies D (1993) The Duhem thesis and the Quine thesis. In: Gillies D (ed) Philosophy of science in the twentieth century. Blackwell, Oxford, pp 98–116

Kukla A (1993) Laudan, Leplin, empirical equivalence and underdetermination. Analysis 53:1–7

Kukla A (1996) Does every theory have empirically equivalent rivals? Erkenntnis 44:137–166

Article   Google Scholar  

Laudan L, Leplin J (1991) Empirical equivalence and underdetermination. J Philos 88:449–472

Norton J (2008) Must evidence underdetermine theory? In: Carrier M, Howard D, Kourany J (eds) The Challenge of the social and the pressure of practice: science and values revisited. University of Pittsburgh Press, Pittsburgh, pp 17–44

Quine WVO (1953) Two dogmas of empiricism. In: Quine WVO (ed) From a logical point of view. Nine logico-philosophical essays. Harvard University Press, Cambridge, MA, pp 20–46, 1971

Quine WVO, Ullian JS (1978) The web of belief, 2nd edn. Random House, New York

Stanford PK (2006) Exceeding our grasp: science, history, and the problem of unconceived alternatives. Oxford University Press, New York

Book   Google Scholar  

Stanford PK (2009) Underdetermination of scientific theory. In: Zalta E.N. (ed.) The Stanford Encyclopedia of Philosophy. URL = http://plato.stanford.edu/entries/scientific-underdetermination/notes.html#2

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Carrier, M. (2013). Underdetermination. In: Dubitzky, W., Wolkenhauer, O., Cho, KH., Yokota, H. (eds) Encyclopedia of Systems Biology. Springer, New York, NY. https://doi.org/10.1007/978-1-4419-9863-7_121

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Underdetermination Versus Indeterminacy

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Underdetermination of Scientific Theory

At the heart of the underdetermination of scientific theory by evidence is the simple idea that the evidence available to us at a given time may be insufficient to determine what beliefs we should hold in response to it. In a textbook example, if I know that you spent $10 on apples and oranges and that apples cost $1 while oranges cost $2, then I know that you did not buy six oranges, but I do not know whether you bought one orange and eight apples, two oranges and six apples, and so on. A simple scientific example can be found in the rationale behind the important methodological adage that “correlation does not imply causation”. If playing violent video games causes children to be more aggressive in their playground behavior, then we should (barring complications) expect to find a correlation between time spent playing such video games and aggressive behavior on the playground. But that is also what we would expect to find if children who are prone to aggressive behavior tend to enjoy and seek out violent video games more than other children, or if propensities for playing violent video games and for aggressive playground behavior are both caused by some third factor (like being bullied or general parental neglect). So a high correlation between time spent playing violent video games and aggressive playground behavior (by itself) simply underdetermines what we should believe about the causal relationship between the two. But it turns out that this simple and familiar predicament only scratches the surface of the various ways in which problems of underdetermination can arise in the course of scientific investigation.

1. A First Look: Duhem, Quine, and the Problems of Underdetermination

2.1 holist underdetermination: the very idea, 2.2 challenging the rationality of science, 3.1 contrastive underdetermination: back to duhem, 3.2 empirically equivalent theories, 3.3 unconceived alternatives and a new induction, other internet resources, related entries.

The scope of the epistemic challenge arising from underdetermination is not limited only to scientific contexts, as is perhaps most readily seen in classical skeptical attacks on our knowledge more generally. René Descartes ([1640] 1996) famously sought to doubt any and all of his beliefs which could possibly be doubted by supposing that there might be an all-powerful Evil Demon who sought to deceive him. Descartes’ challenge appeals to a form of underdetermination: he notes that all our sensory experiences would be just the same if they were caused by this Evil Demon rather than an external world of rocks and trees. Likewise, Nelson Goodman’s (1955) “New Riddle of Induction” turns on the idea that the evidence we now have could equally well be taken to support inductive generalizations quite different from those we usually take them to support, with radically different consequences for the course of future events. [ 1 ] Nonetheless, underdetermination has been thought to arise in scientific contexts in a variety of distinctive and important ways that do not simply recreate such radically skeptical possibilities.

The traditional locus classicus for underdetermination in science is the work of Pierre Duhem, a French physicist as well as historian and philosopher of science who lived at the turn of the 20 th Century. In The Aim and Structure of Physical Theory , Duhem formulated various problems of scientific underdetermination in an especially perspicuous and compelling way, although he himself argued that these problems posed serious challenges only to our efforts to confirm theories in physics. In the middle of the 20 th Century, W. V. O. Quine suggested that such challenges applied not only to the confirmation of all types of scientific theories, but to all knowledge claims whatsoever. His incorporation and further development of these problems as part of a general account of human knowledge was one of the most significant developments of 20 th Century epistemology. But neither Duhem nor Quine was careful to systematically distinguish a number of fundamentally distinct lines of thinking about underdetermination found in their work. Perhaps the most important division is between what we might call holist and contrastive forms of underdetermination. Holist underdetermination (Section 2 below) arises whenever our inability to test hypotheses in isolation leaves us underdetermined in our response to a failed prediction or some other piece of disconfirming evidence. That is, because hypotheses have empirical implications or consequences only when conjoined with other hypotheses and/or background beliefs about the world, a failed prediction or falsified empirical consequence typically leaves open to us the possibility of blaming and abandoning one of these background beliefs and/or ‘auxiliary’ hypotheses rather than the hypothesis we set out to test in the first place. But contrastive underdetermination (Section 3 below) involves the quite different possibility that for any body of evidence confirming a theory, there might well be other theories that are also well confirmed by that very same body of evidence. Moreover, claims of underdetermination of either of these two fundamental varieties can vary in strength and character in any number of ways: one might, for example, suggest that the choice between two theories or two ways of revising our beliefs is transiently underdetermined simply by the evidence we happen to have at present , or instead permanently underdetermined by all possible evidence. Indeed, the variety of forms of underdetermination that confront scientific inquiry, and the causes and consequences claimed for these different varieties, are sufficiently heterogeneous that attempts to address “the” problem of underdetermination for scientific theories have often engendered considerable confusion and argumentation at cross-purposes. [ 2 ]

Moreover, such differences in the character and strength of various claims of underdetermination turn out to be crucial for resolving the significance of the issue. For example, in some recently influential discussions of science it has become commonplace for scholars in a wide variety of academic disciplines to make casual appeal to claims of underdetermination (especially of the holist variety) to support the idea that something besides evidence must step in to do the further work of determining beliefs and/or changes of belief in scientific contexts. Perhaps most prominent among these are adherents of the sociology of scientific knowledge (SSK) movement and some feminist science critics who have argued that it is typically the sociopolitical interests and/or pursuit of power and influence by scientists themselves which play a crucial and even decisive role in determining which beliefs are actually abandoned or retained in response to conflicting evidence. As we will see in Section 2.2, however, Larry Laudan has argued that such claims depend upon simple equivocation between comparatively weak or trivial forms of underdetermination and the far stronger varieties from which they draw radical conclusions about the limited reach of evidence and rationality in science. In the sections that follow we will seek to clearly characterize and distinguish the various forms of both holist and contrastive underdetermination that have been suggested to arise in scientific contexts (noting some important connections between them along the way), assess the strength and significance of the heterogeneous argumentative considerations offered in support of and against them, and consider just which forms of underdetermination pose genuinely consequential challenges for scientific inquiry.

2. Holist Underdetermination and Challenges to Scientific Rationality

Duhem’s original case for holist underdetermination is, perhaps unsurprisingly, intimately bound up with his arguments for confirmational holism: the claim that theories or hypotheses can only be subjected to empirical testing in groups or collections, never in isolation. The idea here is that a single scientific hypothesis does not by itself carry any implications about what we should expect to observe in nature; rather, we can derive empirical consequences from an hypothesis only when it is conjoined with many other beliefs and hypotheses, including background assumptions about the world, beliefs about how measuring instruments operate, further hypotheses about the interactions between objects in the original hypothesis’ field of study and the surrounding environment, etc. For this reason, Duhem argues, when an empirical prediction is falsified, we do not know whether the fault lies with the hypothesis we originally sought to test or with one of the many other beliefs and hypotheses that were also needed and used to generate the failed prediction:

A physicist decides to demonstrate the inaccuracy of a proposition; in order to deduce from this proposition the prediction of a phenomenon and institute the experiment which is to show whether this phenomenon is or is not produced, in order to interpret the results of this experiment and establish that the predicted phenomenon is not produced, he does not confine himself to making use of the proposition in question; he makes use also of a whole group of theories accepted by him as beyond dispute. The prediction of the phenomenon, whose nonproduction is to cut off debate, does not derive from the proposition challenged if taken by itself, but from the proposition at issue joined to that whole group of theories; if the predicted phenomenon is not produced, the only thing the experiment teaches us is that among the propositions used to predict the phenomenon and to establish whether it would be produced, there is at least one error; but where this error lies is just what it does not tell us. ([1914] 1954, 185)

Duhem supports this claim with examples from physical theory, including one designed to illustrate a celebrated further consequence he draws from it. Holist underdetermination ensures, Duhem argues, that there cannot be any such thing as a “crucial experiment” (experimentum crucis): a single experiment whose outcome is predicted differently by two competing theories and which therefore serves to definitively confirm one and refute the other. For example, in a famous scientific episode intended to resolve the ongoing heated battle between partisans of the theory that light consists of a stream of particles moving at extremely high speed (the particle or “emission” theory of light) and defenders of the view that light consists instead of waves propagated through a mechanical medium (the wave theory), the physicist Foucault designed an apparatus to test the two theories’ competing claims about the speed of transmission of light in different media: the particle theory implied that light would travel faster in water than in air, while the wave theory implied that the reverse was true. Although the outcome of the experiment was taken to show that light travels faster in air than in water, [ 3 ] Duhem argues that this is far from a refutation of the hypothesis of emission:

in fact, what the experiment declares stained with error is the whole group of propositions accepted by Newton, and after him by Laplace and Biot, that is, the whole theory from which we deduce the relation between the index of refraction and the velocity of light in various media. But in condemning this system as a whole by declaring it stained with error, the experiment does not tell us where the error lies. Is it in the fundamental hypothesis that light consists in projectiles thrown out with great speed by luminous bodies? Is it in some other assumption concerning the actions experienced by light corpuscles due to the media in which they move? We know nothing about that. It would be rash to believe, as Arago seems to have thought, that Foucault’s experiment condemns once and for all the very hypothesis of emission, i.e., the assimilation of a ray of light to a swarm of projectiles. If physicists had attached some value to this task, they would undoubtedly have succeeded in founding on this assumption a system of optics that would agree with Foucault’s experiment. ([1914] 1954, p. 187)

From this and similar examples, Duhem drew the quite general conclusion that our response to the experimental or observational falsification of a theory is always underdetermined in this way. When the world does not live up to our theory-grounded expectations, we must give up something , but because no hypothesis is ever tested in isolation, no experiment ever tells us precisely which belief it is that we must revise or give up as mistaken:

In sum, the physicist can never subject an isolated hypothesis to experimental test, but only a whole group of hypotheses; when the experiment is in disagreement with his predictions, what he learns is that at least one of the hypotheses constituting this group is unacceptable and ought to be modified; but the experiment does not designate which one should be changed. ([1914] 1954, 187)

The predicament Duhem here identifies is no mere rainy day puzzle for philosophers of science, but a methodological challenge that consistently arises in the course of scientific practice itself. It is simply not true that for practical purposes and in concrete contexts there is always just a single revision of our beliefs in response to disconfirming evidence that is obviously correct, most promising, or even most sensible to pursue. To cite a classic example, when Newton’s celestial mechanics failed to correctly predict the orbit of Uranus, scientists at the time did not simply abandon the theory but protected it from refutation by instead challenging the background assumption that the solar system contained only seven planets. This strategy bore fruit, notwithstanding the falsity of Newton’s theory: by calculating the location of a hypothetical eighth planet influencing the orbit of Uranus, the astronomers Adams and Leverrier were eventually led to discover Neptune in 1846. But the very same strategy failed when used to try to explain the advance of the perihelion in Mercury’s orbit by postulating the existence of “Vulcan”, an additional planet located between Mercury and the sun, and this phenomenon would resist satisfactory explanation until the arrival of Einstein’s theory of general relativity. So it seems that Duhem was right to suggest not only that hypotheses must be tested as a group or a collection, but also that it is by no means a foregone conclusion which member of such a collection should be abandoned or revised in response to a failed empirical test or false implication. Indeed, this very example illustrates why Duhem’s own rather hopeful appeal to the ‘good sense’ of scientists themselves in deciding when a given hypothesis ought to be abandoned promises very little if any relief from the general predicament of holist underdetermination.

As noted above, Duhem thought that the sort of underdetermination he had described presented a challenge only for theoretical physics, but subsequent thinking in the philosophy of science has tended to the opinion that the predicament Duhem described applies to theoretical testing in all fields of scientific inquiry. We cannot, for example, test an hypothesis about the phenotypic effects of a particular gene without presupposing a host of further beliefs about what genes are, how they work, how we can identify them, what other genes are doing, and so on. In the middle of the 20 th Century, W. V. O. Quine would incorporate confirmational holism and its associated concerns about underdetermination into an extraordinarily influential account of knowledge in general. As part of his famous (1951) critique of the widely accepted distinction between truths that are analytic (true by definition, or as a matter of logic or language alone) and those that are synthetic (true in virtue of some contingent fact about the way the world is), Quine argued that all of the beliefs we hold at any given time are linked in an interconnected web, which encounters our sensory experience only at its periphery:

The totality of our so-called knowledge or beliefs, from the most casual matters of geography and history to the profoundest laws of atomic physics or even of pure mathematics and logic, is a man-made fabric which impinges on experience only along the edges. Or, to change the figure, total science is like a field of force whose boundary conditions are experience. A conflict with experience at the periphery occasions readjustments in the interior of the field. But the total field is so underdetermined by its boundary conditions, experience, that there is much latitude of choice as to what statements to reevaluate in the light of any single contrary experience. No particular experiences are linked with any particular statements in the interior of the field, except indirectly through considerations of equilibrium affecting the field as a whole. (1951, 42–3)

One consequence of this general picture of human knowledge is that all of our beliefs are tested against experience only as a corporate body—or as Quine sometimes puts it, “The unit of empirical significance is the whole of science” (1951, p. 42). [ 4 ] A mismatch between what the web as a whole leads us to expect and the sensory experiences we actually receive will occasion some revision in our beliefs, but which revision we should make to bring the web as a whole back into conformity with our experiences is radically underdetermined by those experiences themselves. To use Quine’s example, if we find our belief that there are brick houses on Elm Street to be in conflict with our immediate sense experience, we might revise our beliefs about the houses on Elm Street, but we might equally well modify instead our beliefs about the appearance of brick, our present location, or innumerable other beliefs constituting the interconnected web. In a pinch, we might even decide that our present sensory experiences are simply hallucinations! Quine’s point was not that any of these are particularly likely or reasonable responses to recalcitrant experiences (indeed, an important part of his account is the explanation of why they are not), but instead that they would serve equally well to bring the web of belief as a whole in line with our experience. And if the belief that there are brick houses on Elm Street were sufficiently important to us, Quine insisted, it would be possible for us to preserve it “come what may” (in the way of empirical evidence), by making sufficiently radical adjustments elsewhere in the web of belief. It is in principle open to us, Quine argued, to revise even beliefs about logic, mathematics, or the meanings of our terms in response to recalcitrant experience; it might seem a tempting solution to certain persistent difficulties in quantum mechanics, for example, to reject classical logic’s law of the excluded middle (allowing physical particles to both have and not have some determinate classical physical property like position or momentum at a given time). The only test of a belief, Quine argued, is whether it fits into a web of connected beliefs that accords well with our experience on the whole . And because this leaves any and all beliefs in that web at least potentially subject to revision on the basis of our ongoing sense experience or empirical evidence, he insisted, there simply are no beliefs that are analytic in the originally supposed sense of immune to revision in light of experience, or true no matter what the world is like.

Quine recognized, of course, that many of the logically possible ways of revising our beliefs in response to recalcitrant experiences that remain open to us nonetheless strike us as ad hoc, perfectly ridiculous, or worse. He argues (1955) that our actual revisions of the web of belief seek to maximize the theoretical “virtues” of simplicity, familiarity, scope, and fecundity, along with conformity to experience, and elsewhere suggests that we typically seek to resolve conflicts between the web of our beliefs and our sensory experiences in accordance with a principle of “conservatism”, that is, by making the smallest possible number of changes to the least central beliefs we can that will suffice to reconcile the web with experience. That is, Quine recognized that when we encounter recalcitrant experience we are not usually at a loss to decide which of our beliefs to revise in response to it, but he claimed that this is simply because we are strongly disposed as a matter of fundamental psychology to prefer whatever revision requires the most minimal mutilation of the existing web of beliefs and/or maximizes virtues that he explicitly recognizes as pragmatic in character. Indeed, it would seem that on Quine’s view the very notion of a belief being more central or peripheral or in lesser or greater “proximity” to sense experience should be cashed out simply as a measure of our willingness to revise it in response to recalcitrant experience. That is, it would seem that what it means for one belief to be located “closer” to the sensory periphery of the web than another is simply that we are more likely to revise the first than the second if doing so would enable us to bring the web as a whole into conformity with otherwise recalcitrant sense experience. Thus, Quine saw the traditional distinction between analytic and synthetic beliefs as simply registering the endpoints of a psychological continuum ordering our beliefs according to the ease and likelihood with which we are prepared to revise them in order to reconcile the web as a whole with our sense experience as a whole.

It is perhaps unsurprising that such holist underdetermination has been taken to pose a threat to the fundamental rationality of the scientific enterprise. The claim that the empirical evidence alone underdetermines our response to failed predictions or recalcitrant experience might even seem to invite the suggestion that what systematically steps into the breach to do the further work of singling out just one or a few candidate responses to disconfirming evidence is something irrational or at least arational in character. Imre Lakatos and Paul Feyerabend each suggested that because of underdetermination, the difference between empirically successful and unsuccessful theories or research programs is largely a function of the differences in talent, creativity, resolve, and resources of those who advocate them. And at least since the influential work of Thomas Kuhn, one important line of thinking about science has held that it is ultimately the social and political interests (in a suitably broad sense) of scientists themselves which serve to determine their responses to disconfirming evidence and therefore the further empirical, methodological, and other commitments of any given scientist or scientific community. Mary Hesse suggests that Quinean underdetermination showed why certain “non-logical” and “extra-empirical” considerations must play a role in theory choice, and claims that “it is only a short step from this philosophy of science to the suggestion that adoption of such criteria, that can be seen to be different for different groups and at different periods, should be explicable by social rather than logical factors” (1980, 33). Perhaps the most prominent modern day defenders of this line of thinking are those scholars in the sociology of scientific knowledge (SSK) movement and in feminist science studies who argue that it is typically the career interests, political affiliations, intellectual allegiances, gender biases, and/or pursuit of power and influence by scientists themselves which play a crucial or even decisive role in determining precisely which beliefs are abandoned or retained when faced with conflicting evidence (classic works in SSK include Bloor 1991, Collins 1992, and Shapin and Schaffer 1985; in feminist science studies, see Longino, 1990, 2002, and for a recent review, Nelson 2022). The shared argumentative schema here is one on which holist underdetermination ensures that the evidence alone cannot do the work of picking out a unique response to failed predictions or recalcitrant experience, thus something else must step in to do the job, and sociologists of scientific knowledge, feminist critics of science, and other interest-driven theorists of science each have their favored suggestions close to hand. (For useful further discussion, see Okasha 2000. Note that historians of science have also appealed to underdetermination in presenting “counterfactual histories” exploring the ways in which important historical developments in science might have turned out quite differently than they actually did; see, for example, Radick 2023.)

In response to this line of argument, Larry Laudan (1990) argues that the significance of such underdetermination has been greatly exaggerated. Underdetermination actually comes in a wide variety of strengths, he insists, depending on precisely what is being asserted about the character, the availability, and (most importantly) the rational defensibility of the various competing hypotheses or ways of revising our beliefs that the evidence supposedly leaves us free to accept. Laudan usefully distinguishes a number of different dimensions along which claims of underdetermination vary in strength, and he goes on to insist that those who attribute dramatic significance to the thesis that our scientific theories are underdetermined by the evidence defend only the weaker versions of that thesis, yet draw dire consequences and shocking morals regarding the character and status of the scientific enterprise from much stronger versions. He suggests, for instance, that Quine’s famous claim that any hypothesis can be preserved “come what may” in the way of evidence can be defended simply as a description of what it is psychologically possible for human beings to do, but Laudan insists that in this form the thesis is simply bereft of interesting or important consequences for epistemology— the study of knowledge . Along this dimension of variation, the strong version of the thesis asserts that it is always normatively or rationally defensible to retain any hypothesis in the light of any evidence whatsoever, but this latter, stronger version of the claim, Laudan suggests, is one for which no convincing evidence or argument has ever been offered. More generally, Lauden argues, arguments for underdetermination turn on implausibly treating all logically possible responses to the evidence as equally justified or rationally defensible. For example, Laudan suggests that we might reasonably hold the resources of deductive logic to be insufficient to single out just one acceptable response to disconfirming evidence, but not that deductive logic plus the sorts of ampliative principles of good reasoning typically deployed in scientific contexts are insufficient to do so. Similarly, defenders of underdetermination might assert the nonuniqueness claim that for any given theory or web of beliefs, either there is at least one alternative that can also be reconciled with the available evidence, or the much stronger claim that all of the contraries of any given theory can be reconciled with the available evidence equally well. And the claim of such “reconciliation” itself disguises a wide range of further alternative possibilities: that our theories can be made logically compatible with any amount of disconfirming evidence (perhaps by the simple expedient of removing any claim(s) with which the evidence is in conflict), that any theory may be reformulated or revised so as to entail any piece of previously disconfirming evidence, or so as to explain previously disconfirming evidence, or that any theory can be made to be as well supported empirically by any collection of evidence as any other theory. And in all of these respects, Laudan claims, partisans have defended only the weaker forms of underdetermination while founding their further claims about and conceptions of the scientific enterprise on versions much stronger than those they have managed or even attempted to defend.

Laudan is certainly right to distinguish these various versions of holist underdetermination, and he is equally right to suggest that many of the thinkers he confronts have derived grand morals concerning the scientific enterprise from much stronger versions of underdetermination than they are able to defend, but the underlying situation is somewhat more complex than he suggests. Laudan’s overarching claim is that champions of holist underdetermination show only that a wide variety of responses to disconfirming evidence are logically possible (or even just psychologically possible), rather than that these are all rationally defensible or equally well-supported by the evidence. But his straightforward appeal to further epistemic resources like ampliative principles of belief revision that are supposed to help narrow the merely logical possibilities down to those which are reasonable or rationally defensible is itself problematic, at least as part of any attempt to respond to Quine. This is because on Quine’s holist picture of knowledge such further ampliative principles governing legitimate belief revision are themselves simply part of the web of our beliefs, and are therefore open to revision in response to recalcitrant experience as well. Indeed, this is true even for the principles of deductive logic and the (consequent) demand for particular forms of logical consistency between parts of the web itself! So while it is true that the ampliative principles we currently embrace do not leave all logically or even psychologically possible responses to the evidence open to us (or leave us free to preserve any hypothesis “come what may”), our continued adherence to these very principles , rather than being willing to revise the web of belief so as to abandon them, is part of the phenomenon to which Quine is using underdetermination to draw our attention, and so cannot be taken for granted without begging the question. Put another way, Quine does not simply ignore the further principles that function to ensure that we revise the web of belief in one way rather than others, but it follows from his account that such principles are themselves part of the web and therefore candidates for revision in our efforts to bring the web of beliefs into conformity (by the resulting web’s own lights) with sensory experience. This recognition makes clear why it will be extremely difficult to say how the shift to an alternative web of belief (with alternative ampliative or even deductive principles of belief revision) should or even can be evaluated for its rational defensibility. Each proposed revision is likely to be maximally rational by the lights of the principles it itself sanctions. [ 5 ] Of course we can rightly say that many candidate revisions would violate our presently accepted ampliative principles of rational belief revision, but the preference we have for those rather than the alternatives is itself simply generated by their position in the web of belief we have inherited, and the role that they themselves play in guiding the revisions we are inclined to make to that web in light of ongoing experience.

Thus, if we accept Quine’s general picture of knowledge, it becomes quite difficult to disentangle normative from descriptive issues, or questions about the psychology of human belief revision from questions about the justifiability or rational defensibility of such revisions. It is in part for this reason that Quine famously suggests (1969, 82; see also p 75–76) that epistemology itself “falls into place as a chapter of psychology and hence of natural science.” His point is not that epistemology should simply be abandoned in favor of psychology, but instead that there is ultimately no way to draw a meaningful distinction between the two. (James Woodward, in comments on an earlier draft of this entry, pointed out that this makes it all the harder to assess the significance of Quinean underdetermination in light of Laudan’s complaint or even know the rules for doing so, but in an important way this difficulty was Quine’s point all along!) Quine’s claim is that “[e]ach man is given a scientific heritage plus a continuing barrage of sensory stimulation; and the considerations which guide him in warping his scientific heritage to fit his continuing sensory promptings are, where rational, pragmatic” (1951, 46), but the role of these pragmatic considerations or principles in selecting just one of the many possible revisions of the web of belief in response to recalcitrant experience is not to be contrasted with those same principles having rational or epistemic justification. Far from conflicting with or even being orthogonal to the search for truth and our efforts to render our beliefs maximally responsive to the evidence, Quine insists, revising our beliefs in accordance with such pragmatic principles “at bottom, is what evidence is” (1955, 251). Whether or not this strongly naturalistic conception of epistemology can ultimately be defended, it is misleading for Laudan to suggest that the thesis of underdetermination becomes trivial or obviously insupportable the moment we inquire into the rational defensibility rather than the mere logical or psychological possibility of alternative revisions to the holist’s web of belief.

In fact, there is an important connection between this lacuna in Laudan’s discussion and the further uses made of the thesis of underdetermination by sociologists of scientific knowledge, feminist epistemologists, and other vocal champions of holist underdetermination. When faced with the invocation of further ampliative standards or principles that supposedly rule out some responses to disconfirmation as irrational or unreasonable, these thinkers typically respond by insisting that the embrace of such further standards or principles (or perhaps their application to particular cases) is itself underdetermined, historically contingent, and/or subject to ongoing social negotiation. For this reason, they suggest, such appeals (and their success or failure in convincing the members of a given community) should be explained by reference to the same broadly social and political interests that they claim are at the root of theory choice and belief change in science more generally (see, e.g., Shapin and Schaffer, 1985). On both accounts, then, our response to recalcitrant evidence or a failed prediction is constrained in important ways by features of the existing web of beliefs. But for Quine, the continuing force of these constraints is ultimately imposed by the fundamental principles of human psychology (such as our preference for minimal mutilation of the web, or the pragmatic virtues of simplicity, fecundity, etc.), while for constructivist theorists of science such as Shapin and Schaffer, the continuing force of any such constraints is limited only by the ongoing negotiated agreement of the communities of scientists who respect them.

As this last contrast makes clear, recognizing the limitations of Laudan’s critique of Quine and the fact that we cannot dismiss holist underdetermination with any straightforward appeal to ampliative principles of good reasoning by itself does nothing to establish the further positive claims about belief revision advanced by interest-driven theorists of science. Conceding that theory choice or belief revision in science is underdetermined by the evidence in just the ways that Duhem and/or Quine suggested leaves entirely open whether it is instead the (suitably broad) social or political interests of scientists themselves that do the further work of singling out the particular beliefs or responses to falsifying evidence that any particular scientist or scientific community will actually adopt or find compelling. Even many of those philosophers of science who are most strongly convinced of the general significance of various forms of underdetermination remain deeply skeptical of this latter thesis and thoroughly unconvinced by the empirical evidence that has been offered in support of it (usually in the form of case studies of particular historical episodes in science).

Appeals to underdetermination have also loomed large in recent philosophical debates concerning the place of values in science, with a number of authors arguing that the underdetermination of theory by data is among the central reasons that values (or “non-epistemic” values) do and perhaps must play a central role in scientific inquiry. Feminist philosophers of science have sometimes suggested that it is such underdetermination which creates room not only for unwarranted androcentric values or assumptions to play central roles in the embrace of particular theoretical possibilities, but also for the critical and alternative approaches favored by feminists themselves (e.g. Nelson 2022). But appeals to underdetermination also feature prominently in more general arguments against the possibility or desirability of value-free science. Perhaps most influentially, Helen Longino’s “contextual empiricism” suggests that a wide variety of non-epistemic values play important roles in determining our scientific beliefs in part because underdetermination prevents data or evidence alone from doing so. For this and other reasons she concludes that objectivity in science is therefore best served by a diverse set of participants who bring a variety of different values or value-laden assumptions to the enterprise (Longino 1990, 2002).

3. Contrastive Underdetermination, Empirical Equivalents, and Unconceived Alternatives

Although it is also a form of underdetermination, what we described in Section 1 above as contrastive underdetermination raises fundamentally different issues from the holist variety considered in Section 2 (Bonk 2008 raises many of these issues). John Stuart Mill articulated the challenge of contrastive underdetermination with impressive clarity in A System of Logic , where he writes:

Most thinkers of any degree of sobriety allow, that an hypothesis...is not to be received as probably true because it accounts for all the known phenomena, since this is a condition sometimes fulfilled tolerably well by two conflicting hypotheses...while there are probably a thousand more which are equally possible, but which, for want of anything analogous in our experience, our minds are unfitted to conceive. ([1867] 1900, 328)

This same concern is also evident in Duhem’s original writings concerning so-called crucial experiments, where he seeks to show that even when we explicitly suspend any concerns about holist underdetermination, the contrastive variety remains an obstacle to our discovery of truth in theoretical science:

But let us admit for a moment that in each of these systems [concerning the nature of light] everything is compelled to be necessary by strict logic, except a single hypothesis; consequently, let us admit that the facts, in condemning one of the two systems, condemn once and for all the single doubtful assumption it contains. Does it follow that we can find in the ‘crucial experiment’ an irrefutable procedure for transforming one of the two hypotheses before us into a demonstrated truth? Between two contradictory theorems of geometry there is no room for a third judgment; if one is false, the other is necessarily true. Do two hypotheses in physics ever constitute such a strict dilemma? Shall we ever dare to assert that no other hypothesis is imaginable? Light may be a swarm of projectiles, or it may be a vibratory motion whose waves are propagated in a medium; is it forbidden to be anything else at all? ([1914] 1954, 189)

Contrastive underdetermination is so-called because it questions the ability of the evidence to confirm any given hypothesis against alternatives , and the central focus of discussion in this connection (equally often regarded as “the” problem of underdetermination) concerns the character of the supposed alternatives. Of course the two problems are not entirely disconnected, because it is open to us to consider alternative possible modifications of the web of beliefs as alternative theories between which the empirical evidence alone is powerless to decide. But we have already seen that one need not think of the alternative responses to recalcitrant experience as competing theoretical alternatives to appreciate the character of the holist’s challenge, and we will see that one need not embrace any version of holism about confirmation to appreciate the quite distinct problem that the available evidence might support more than one theoretical alternative. It is perhaps most useful here to think of holist underdetermination as starting from a particular theory or body of beliefs and claiming that our revision of those beliefs in response to new evidence may be underdetermined, while contrastive underdetermination instead starts from a given body of evidence and claims that more than one theory may be well-supported by that evidence. Part of what has contributed to the conflation of these two problems is the holist presuppositions of those who originally made them famous. After all, on Quine’s view, we simply revise the web of belief in response to recalcitrant experience, and so the suggestion that there are multiple possible revisions of the web available in response to any particular evidential finding just is the claim that there are in fact many different “theories” (i.e. candidate webs of belief) that are equally well-supported by any given body of data. [ 6 ] But if we give up such extreme holist views of evidence, meaning, and/or confirmation, the two problems take on very different identities, with very different considerations in favor of taking them seriously, very different consequences, and very different candidate solutions. Notice, for instance, that even if we somehow knew that no other hypothesis on a given subject was well-confirmed by a given body of data, that would not tell us where to place the blame or which of our beliefs to give up if the remaining hypothesis in conjunction with others subsequently resulted in a failed empirical prediction. And as Duhem suggests in the passage cited above, even if we supposed that we somehow knew exactly which of our hypotheses to blame in response to a failed empirical prediction, this would not help us to decide whether or not there are other hypotheses available that are also well-confirmed by the data we actually have.

One way to see why not is to consider an analogy that champions of contrastive underdetermination have sometimes used to support their case. If we consider any finite group of data points, an elementary proof reveals that there are an infinite number of distinct mathematical functions describing different curves that will pass through all of them. As we add further data to our initial set we will eliminate functions describing curves which no longer capture all of the data points in the new, larger set, but no matter how much data we accumulate, there will always be an infinite number of functions remaining that define curves including all the data points in the new set and which would therefore seem to be equally well supported by the empirical evidence. No finite amount of data will ever be able to narrow the possibilities down to just a single function or indeed, any finite number of candidate functions, from which the distribution of data points we have might have been generated. Each new data point we gather eliminates an infinite number of curves that previously fit all the data (so the problem here is not the holist’s challenge that we do not know which beliefs to give up in response to failed predictions or disconfirming evidence), but also leaves an infinite number still in contention.

Of course, generating and testing fundamental scientific hypotheses is rarely if ever a matter of finding curves that fit collections of data points, so nothing follows directly from this mathematical analogy for the significance of contrastive underdetermination in most scientific contexts. But Bas van Fraassen has offered an extremely influential line of argument intended to show that such contrastive underdetermination is a serious concern for scientific theorizing more generally. In The Scientific Image (1980), van Fraassen uses a now-classic example to illustrate the possibility that even our best scientific theories might have empirical equivalents : that is, alternative theories making the very same empirical predictions, and which therefore cannot be better or worse supported by any possible body of evidence. Consider Newton’s cosmology, with its laws of motion and gravitational attraction. As Newton himself realized, exactly the same predictions are made by the theory whether we assume that the entire universe is at rest or assume instead that it is moving with some constant velocity in any given direction: from our position within it, we have no way to detect constant, absolute motion by the universe as a whole. Thus, van Fraassen argues, we are here faced with empirically equivalent scientific theories: Newtonian mechanics and gravitation conjoined either with the fundamental assumption that the universe is at absolute rest (as Newton himself believed), or with any one of an infinite variety of alternative assumptions about the constant velocity with which the universe is moving in some particular direction. All of these theories make all and only the same empirical predictions, so no evidence will ever permit us to decide between them on empirical grounds. [ 7 ]

Van Fraassen is widely (though mistakenly) regarded as holding that the prospect of contrastive underdetermination grounded in such empirical equivalents demands that we restrict our epistemic ambitions for the scientific enterprise itself. His constructive empiricism holds that the aim of science is not to find true theories, but only theories that are empirically adequate: that is, theories whose claims about observable phenomena are all true. Since the empirical adequacy of a theory is not threatened by the existence of another that is empirically equivalent to it, fulfilling this aim has nothing to fear from the possibility of such empirical equivalents. In reply, many critics have suggested that van Fraassen gives no reasons for restricting belief to empirical adequacy that could not also be used to argue for suspending our belief in the future empirical adequacy of our best present theories. Of course there could be empirical equivalents to our best theories, but there could also be theories equally well-supported by all the evidence up to the present which diverge in their predictions about observables in future cases not yet tested. This challenge seems to miss the point of van Fraassen’s epistemic voluntarism: his claim is that we should believe no more but also no less than we need to take full advantage of our scientific theories, and a commitment to the empirical adequacy of our theories, he suggests, is the least we can get away with in this regard. Of course it is true that we are running some epistemic risk in believing in even the full empirical adequacy of our present theories, but this is the minimum we need to take full advantage of the fruits of our scientific labors, and the risk is considerably less than what we assume in believing in their truth: as van Fraassen famously suggests, “it is not an epistemic principle that one might as well hang for a sheep as a lamb” (1980, 72).

In an influential discussion, Larry Laudan and Jarrett Leplin (1991) argue that philosophers of science have invested even the bare possibility that our theories might have empirical equivalents with far too much epistemic significance. Notwithstanding the popularity of the presumption that there are empirically equivalent rivals to every theory, they argue, the conjunction of several familiar and relatively uncontroversial epistemological theses is sufficient to defeat it. Because the boundaries of what is observable change as we develop new experimental methods and instruments, because auxiliary assumptions are always needed to derive empirical consequences from a theory (cf. confirmational holism, above), and because these auxiliary assumptions are themselves subject to change over time, Laudan and Leplin conclude that there is no guarantee that any two theories judged to be empirically equivalent at a given time will remain so as the state of our knowledge advances. Accordingly, any judgment of empirical equivalence is both defeasible and relativized to a particular state of science. So even if two theories are empirically equivalent at a given time this is no guarantee that they will remain so, and thus there is no foundation for a general pessimism about our ability to distinguish theories that are empirically equivalent to each other on empirical grounds. Although they concede that we could have good reason to think that particular theories have empirically equivalent rivals, this must be established case-by-case rather than by any general argument or presumption.

One fairly standard reply to this line of argument is to suggest that what Laudan and Leplin really show is that the notion of empirical equivalence must be applied to larger collections of beliefs than those traditionally identified as scientific theories—at least large enough to encompass the auxiliary assumptions needed to derive empirical predictions from them. At the extreme, perhaps this means that the notion of empirical equivalents (or at least timeless empirical equivalents) cannot be applied to anything less than “systems of the world” (i.e. total Quinean webs of belief), but even that is not fatal: what the champion of contrastive underdetermination asserts is that there are empirically equivalent systems of the world that incorporate different theories of the nature of light, or spacetime, or whatever (for useful discussion, see Okasha 2002). On the other hand, it might seem that quick examples like van Fraassen’s variants of Newtonian cosmology do not serve to make this thesis as plausible as the more limited claim of empirical equivalence for individual theories. It seems equally natural, however, to respond to Laudan and Leplin simply by conceding the variability in empirical equivalence but insisting that this is not enough to undermine the problem. Empirical equivalents create a serious obstacle to belief in a theory so long as there is some empirical equivalent to that theory at any given time, but it need not be the same one at each time. On this line of thinking, cases like van Fraassen’s Newtonian example illustrate how easy it is for theories to admit of empirical equivalents at any given time, and thus constitute a reason for thinking that there probably are or will be empirical equivalents to any given theory at any particular time, assuring that whenever the question of belief in a given theory arises, the challenge posed to it by contrastive underdetermination arises as well.

Laudan and Leplin also suggest, however, that even if the universal existence of empirical equivalents were conceded, this would do much less to establish the significance of underdetermination than its champions have supposed, because “theories with exactly the same empirical consequences may admit of differing degrees of evidential support” (1991, 465). A theory may be better supported than an empirical equivalent, for instance, because the former but not the latter is derivable from a more general theory whose consequences include a third, well supported, hypothesis. More generally, the belief-worthiness of an hypothesis depends crucially on how it is connected or related to other things we believe and the evidential support we have for those other beliefs. [ 8 ] Laudan and Leplin suggest that we have invited the specter of rampant underdetermination only by failing to keep this familiar home truth in mind and instead implausibly identifying the evidence bearing on a theory exclusively with the theory’s own entailments or empirical consequences (but cf. Tulodziecki 2012). This impoverished view of evidential support, they argue, is in turn the legacy of a failed foundationalist and positivistic approach to the philosophy of science which mistakenly assimilates epistemic questions about how to decide whether or not to believe a theory to semantic questions about how to establish a theory’s meaning or truth-conditions.

John Earman (1993) has argued that this dismissive diagnosis does not do justice to the threat posed by underdetermination. He argues that worries about underdetermination are an aspect of the more general question of the reliability of our inductive methods for determining beliefs, and notes that we cannot decide how serious a problem underdetermination poses without specifying (as Laudan and Leplin do not) the inductive methods we are considering. Earman regards some version of Bayesianism as our most promising form of inductive methodology, and he proceeds to show that challenges to the long-run reliability of our Bayesian methods can be motivated by considerations of the empirical indistinguishability (in several different and precisely specified senses) of hypotheses stated in any language richer than that of the evidence itself that do not amount simply to general skepticism about those inductive methods. In other words, he shows that there are more reasons to worry about underdetermination concerning inferences to hypotheses about unobservables than to, say, inferences about unobserved observables. He also goes on to argue that at least two genuine cosmological theories have serious, nonskeptical, and nonparasitic empirical equivalents: the first essentially replaces the gravitational field in Newtonian mechanics with curvature in spacetime itself, [ 9 ] while the second recognizes that Einstein’s General Theory of Relativity permits cosmological models exhibiting different global topological features which cannot be distinguished by any evidence inside the light cones of even idealized observers who live forever. [ 10 ] And he suggests that “the production of a few concrete examples is enough to generate the worry that only a lack of imagination on our part prevents us from seeing comparable examples of underdetermination all over the map” (1993, 31) even as he concedes that his case leaves open just how far the threat of underdetermination extends (1993, 36).

Most philosophers of science, however, have not embraced the idea that it is only lack of imagination which prevents us from finding empirical equivalents to our scientific theories generally. They note that the convincing examples of empirical equivalents we do have are all drawn from a single domain of highly mathematized scientific theorizing in which the background constraints on serious theoretical alternatives are far from clear, and suggest that it is therefore reasonable to ask whether even a small handful of such examples should make us believe that there are probably empirical equivalents to most of our scientific theories most of the time. They concede that it is always possible that there are empirical equivalents to even our best scientific theories concerning any domain of nature, but insist that we should not be willing to suspend belief in any particular theory until some convincing alternative to it can actually be produced: as Philip Kitcher puts it, “give us a rival explanation, and we’ll consider whether it is sufficiently serious to threaten our confidence” (1993, 154; see also Leplin 1997, Achinstein 2002). That is, these thinkers insist that until we are able to actually construct an empirically equivalent alternative to a given theory, the bare possibility that such equivalents exist is insufficient to justify suspending belief in the best theories we do have. For this same reason most philosophers of science are unwilling to follow van Fraassen into what they regard as constructive empiricism’s unwarranted epistemic modesty. Even if van Fraassen is right about the most minimal beliefs we must hold in order to take full advantage of our scientific theories, most thinkers do not see why we should believe the least we can get away with rather than believing the most we are entitled to by the evidence we have.

Champions of contrastive underdetermination have most frequently responded by trying to establish that all theories have empirical equivalents, typically by proposing something like an algorithmic procedure for generating such equivalents from any theory whatsoever. Stanford (2001, 2006) suggests that these efforts to prove that all our theories must have empirical equivalents fall roughly but reliably into global and local varieties, and that neither makes a convincing case for a distinctive scientific problem of contrastive underdetermination. Global algorithms are well-represented by Andre Kukla’s (1996) suggestion that from any theory T we can immediately generate such empirical equivalents as T ′ (the claim that T ’s observable consequences are true, but T itself is false), T ″ (the claim that the world behaves according to T when observed, but some specific incompatible alternative otherwise), and the hypothesis that our experience is being manipulated by powerful beings in such a way as to make it appear that T is true. But such possibilities, Stanford argues, amount to nothing more than the sort of Evil Deceiver to which Descartes appealed in order to doubt any of his beliefs that could possibly be doubted (see Section 1, above). Such radically skeptical scenarios pose an equally powerful (or powerless) challenge to any knowledge claim whatsoever, no matter how it is arrived at or justified, and thus pose no special problem or challenge for beliefs offered to us by theoretical science. If global algorithms like Kukla’s are the only reasons we can give for taking underdetermination seriously in a scientific context, then there is no distinctive problem of the underdetermination of scientific theories by data, only a salient reminder of the irrefutability of classically Cartesian or radical skepticism. [ 11 ]

In contrast to such global strategies for generating empirical equivalents, local algorithmic strategies instead begin with some particular scientific theory and proceed to generate alternative versions that will be equally well supported by all possible evidence. This is what van Fraassen does with the example of Newtonian cosmology, showing that an infinite variety of supposed empirical equivalents can be produced by ascribing different constant absolute velocities to the universe as a whole. But Stanford suggests that empirical equivalents generated in this way are also insufficient to show that there is a distinctive and genuinely troubling form of underdetermination afflicting scientific theories, because they rely on simply saddling particular scientific theories with further claims for which those theories themselves (together with whatever background beliefs we actually hold) imply that we cannot have any evidence. Such empirical equivalents invite the natural response that they simply tack on to our theories further commitments that are or should be no part of those theories themselves. Such claims, it seems, should simply be excised from our theories, leaving over just the claims that sensible defenders would have held were all we were entitled to believe by the evidence in any case. In van Fraassen’s Newtonian example, for instance, this could be done simply by undertaking no commitment concerning the absolute velocity and direction (or lack thereof) of the universe as a whole. Note also that if we believe a given scientific theory when one of the empirical equivalents we could generate from it by the local algorithmic strategy is correct instead, most of what we originally believed will nonetheless turn out to be straightforwardly true.

Stanford (2001, 2006) concludes that no convincing general case has been made for the presumption that there are empirically equivalent rivals to all or most scientific theories, or to any theories besides those for which such equivalents can actually be constructed. But he goes on to insist that empirical equivalents are no essential part of the case for a significant problem of contrastive underdetermination. Our efforts to confirm scientific theories, he suggests, are no less threatened by what Larry Sklar (1975, 1981) has called “transient” underdetermination, that is, theories which are not empirically equivalent but are equally (or at least reasonably) well confirmed by all the evidence we happen to have in hand at the moment, so long as this transient predicament is also “recurrent”, that is, so long as we think that there is (probably) at least one such (fundamentally distinct) alternative available—and thus the transient predicament re-arises—whenever we are faced with a decision about whether to believe a given theory at a given time. Stanford argues that a convincing case for contrastive underdetermination of this recurrent, transient variety can indeed be made, and that the evidence for it is available in the historical record of scientific inquiry itself.

Stanford concedes that present theories are not transiently underdetermined by the theoretical alternatives we have actually developed and considered to date: we think that our own scientific theories are considerably better confirmed by the evidence than any rivals we have actually produced. The central question, he argues, is whether we should believe that there are well confirmed alternatives to our best scientific theories that are presently unconceived by us. And the primary reason we should believe that there are, he claims, is the long history of repeated transient underdetermination by previously unconceived alternatives across the course of scientific inquiry. In the progression from Aristotelian to Cartesian to Newtonian to contemporary mechanical theories, for instance, the evidence available at the time each earlier theory dominated the practice of its day also offered compelling support for each of the later alternatives (unconceived at the time) that would ultimately come to displace it. Stanford’s “New Induction” over the history of science claims that this situation is typical; that is, that “we have, throughout the history of scientific inquiry and in virtually every scientific field, repeatedly occupied an epistemic position in which we could conceive of only one or a few theories that were well confirmed by the available evidence, while subsequent inquiry would routinely (if not invariably) reveal further, radically distinct alternatives as well confirmed by the previously available evidence as those we were inclined to accept on the strength of that evidence” (2006, 19). In other words, Stanford claims that in the past we have repeatedly failed to exhaust the space of fundamentally distinct theoretical possibilities that were well confirmed by the existing evidence, and that we have every reason to believe that we are probably also failing to exhaust the space of such alternatives that are well confirmed by the evidence we have at present. Much of the rest of his case is taken up with discussing historical examples illustrating that earlier scientists did not simply ignore or dismiss, but instead genuinely failed to conceive of the serious, fundamentally distinct theoretical possibilities that would ultimately come to displace the theories they defended, only to be displaced in turn by others that were similarly unconceived at the time. He concludes that “the history of scientific inquiry itself offers a straightforward rationale for thinking that there typically are alternatives to our best theories equally well confirmed by the evidence, even when we are unable to conceive of them at the time” (2006, 20; for reservations and criticisms concerning this line of argument, see Magnus 2006, 2010; Godfrey-Smith 2008; Chakravartty 2008; Devitt 2011; Ruhmkorff 2011; Lyons 2013). Stanford concedes, however, that the historical record can offer only fallible evidence of a distinctive, general problem of contrastive scientific underdetermination, rather than the kind of deductive proof that champions of the case from empirical equivalents have typically sought. Thus, claims and arguments about the various forms that underdetermination may take, their causes and consequences, and the further significance they hold for the scientific enterprise as a whole continue to evolve in the light of ongoing controversy, and the underdetermination of scientific theory by evidence remains very much a live and unresolved issue in the philosophy of science.

• Achinstein, P., 2002, “Is There A Valid Experimental Argument for Scientific Realism?”, Journal of Philosophy , 99: 470–495.
• Bloor, D., 1981 [1976], Knowledge and Social Imagery , Chicago: University of Chicago, 2nd edition
• Bonk, T., 2008, Underdetermination: An Essay on Evidence and the Limits of Natural Knowledge , Dordrecht, The Netherlands: Springer.
• Belot, G., 2015, “Down to Earth Underdetermination”, Philosophy and Phenomenological Research , 91: 455–464.
• Butterfield, J., 2014, “On Underdetermination in Cosmology”, Studies in History and Philosophy of Modern Physics , 46: 57–69.
• Carman, C., 2005, “The Electrons of the Dinosaurs and the Center of the Earth”, Studies in History and Philosophy of Science , 36: 171–174.
• Chakravartty, A., 2008, “What You Don’t Know Can’t Hurt You: Realism and the Unconceived”, Philosophical Studies , 137: 149–158.
• Cleland, C., 2002, “Methodological and Epistemic Differences Between Historical Science and Experimental Science”, Philosophy of Science , 69: 474–496.
• Collins, H., 1992 [1985], Changing Order: Replication and Induction in Scientific Practice , Chicago: University of Chicago Press, 2nd edition.
• Currie, A., 2018, Rock, Bone, and Ruin , Cambridge, MA: MIT University Press.
• Currie, A. and Sterelny, K., 2017, “In Defence of Story-telling”, Studies in History and Philosophy of Science (Part A), 62: 12–21.
• Descartes, R., [1640] 1996, Meditations on First Philosophy , trans. by John Cottingham, Cambridge: Cambridge University Press.
• Devitt, M., 2011, “Are Unconceived Alternatives a Problem for Scientific Realism”, Journal for General Philosophy of Science , 42: 285–293.
• Duhem, P., [1914] 1954, The Aim and Structure of Physical Theory , trans. from 2 nd ed. by P. W. Wiener; originally published as La Théorie Physique: Son Objet et sa Structure (Paris: Marcel Riviera & Cie.), Princeton, NJ: Princeton University Press.
• Earman, J., 1993, “Underdetermination, Realism, and Reason”, Midwest Studies in Philosophy , 18: 19–38.
• Feyerabend, P., 1975, Against Method , London: Verso.
• Fletcher, S.C., 2021, “The Role of Replication in Psychological Science”, European Journal for Philosophy of Science , 11: 1–19.
• Forber, P. and Griffith, E., 2011, “Historical Reconstruction: Gaining Epistemic Access to the Deep Past”, Philosophy and Theory in Biology , 3. doi:10.3998/ptb.6959004.0003.003
• Gilles, D., 1993, “The Duhem Thesis and the Quine Thesis,”, in Philosophy of Science in the Twentieth Century , Oxford: Blackwell Publishers, pp. 98–116.
• Glymour, C., 1970, “Theoretical Equivalence and Theoretical Realism”, Proceedings of the Biennial Meeting of the Philosophy of Science Association , 1970: 275–288.
• –––, 1977, “The Epistemology of Geometry”, Noûs , 11: 227–251.
• –––, 1980, Theory and Evidence , Princeton, NJ.: Princeton University Press.
• –––, 2013, “Theoretical Equivalence and the Semantic View of Theories”, Philosophy of Science , 80: 286–297.
• Godfrey-Smith, P., 2008, “Recurrent, Transient Underdetermination and the Glass Half-Full”, Philosophical Studies , 137: 141–148.
• Goodman, N., 1955, Fact, Fiction, and Forecast , Indianapolis: Bobbs-Merrill.
• Halvorson, H., 2012, “What Scientific Theories Could Not Be”, Philosophy of Science , 79: 183–206.
• –––, 2013, “The Semantic View, If Plausible, Is Syntactic”, Philosophy of Science , 80: 475–478.
• Hesse, M., 1980, Revolutions and Reconstructions in the Philosophy of Science , Brighton: Harvester Press.
• Kitcher, P., 1993, The Advancement of Science , New York: Oxford University Press.
• Kovaka, K., 2019, “Underdetermination and Evidence in the Developmental Plasticity Debate”, British Journal for the Philosophy of Science , 70: 127–152.
• Kuhn, T., [1962] 1996, The Structure of Scientific Revolutions , Chicago: University of Chicago Press, 3 rd edition.
• Kukla, A., 1996, “Does Every Theory Have Empirically Equivalent Rivals?”, Erkenntnis , 44: 137–166.
• Lakatos, I. 1970, “Falsification and the Methodology of Scientific Research Programmes”, in Criticism and the Growth of Knowledge , I. Lakatos and A. Musgrave (eds.), Cambridge: Cambridge University Press, pp. 91–196.
• Laudan, L., 1990, “Demystifying Underdetermination”, in Scientific Theories , C. Wade Savage (ed.), (Series: Minnesota Studies in the Philosophy of Science, vol. 14), Minneapolis: University of Minnesota Press, pp. 267–297.
• Laudan, L. and Leplin, J., 1991, “Empirical Equivalence and Underdetermination”, Journal of Philosophy , 88: 449–472.
• Leplin, J., 1997, A Novel Defense of Scientific Realism , New York: Oxford University Press.
• Longino, H., 1990, Science as Social Knowledge , Princeton: Princeton University Press.
• –––, 2002, The Fate of Knowledge , Princeton: Princeton University Press.
• Lyons, T., 2013, “A Historically Informed Modus Ponens Against Scientific Realism: Articulation, Critique, and Restoration”, International Studies in the Philosophy of Science , 27: 369–392.
• Magnus, P. 2006, “What’s New About the New Induction?”, Synthese , 148: 295–301.
• –––, 2010, “Inductions, Red Herrings, and the Best Explanation for the Mixed Record of Science”, British Journal for the Philosophy of Science , 61: 803–819.
• Manchak, J. 2009, “Can We Know the Global Structure of Spacetime?”, Studies in History and Philosophy of Modern Physics , 40: 53–56.
• Mill, J. S., [1867] 1900, A System of Logic, Ratiocinative and Inductive, Being a Connected View of the Principles of Evidence and the Methods of Scientific Investigation , New York: Longmans, Green, and Co.
• Miyake, T., 2015, “Underdetermination and Decomposition in Kepler’s Astronomia Nova”, Studies in History and Philosophy of Science , 50: 20–27.
• Nelson, L. H., 2022, “Underdetermination, Holism, and Feminist Philosophy of Science”, Synthese , 200(50). first online 27 February 2022. doi:10.1007/s11229-022-03569-2
• Norton, J. 2008, “Must Evidence Underdetermine Theory?”, in The Challenge of the Social and the Pressure of Practice: Science and Values Revisited , M. Carrier, D. Howard, and J. Kourany (eds.), Pittsburgh: University of Pittsburgh Press, 17–44.
• Okasha, S., 2000, “The Underdetermination of Theory by Data and the ‘Strong Programme’ in the Sociology of Knowledge”, International Studies in thePhilosophy of Science , 14: 283–297.
• –––, 2002, “Underdetermination, Holism, and the Theory/Data Distinction”, The Philosophical Quarterly , 52: 303–319.
• Pietsch, W., 2012, “Hidden Underdetermination: A Case Study in Classical Electrodynamics”, International Studies in the Philosophy of Science , 26: 125–151.
• Quine, W. V. O., 1951, “Two Dogmas of Empiricism”, Reprinted in From a Logical Point of View , 2 nd Ed., Cambridge, MA: Harvard University Press, pp. 20–46.
• –––, 1955, “Posits and Reality”, reprinted in The Ways of Paradox and Other Essays , 2 nd Ed., Cambridge, MA: Harvard University Press, pp. 246–254.
• –––, 1969, “Epistemology Naturalized”, in Ontological Relativity and Other Essays , New York: Columbia University Press, pp. 69–90.
• –––, 1975, “On Empirically Equivalent Systems of the World”, Erkenntnis , 9: 313–328.
• –––, 1990, “Three Indeterminacies”, in Perspectives on Quine , R. B. Barrett and R. F. Gibson, (eds.), Cambridge, MA: Blackwell, pp. 1–16.
• Radick, G., 2023, Disputed Inheritance: The Battle over Mendel and the Future of Biology , Chicago: University of Chicago Press.
• Ruhmkorff, S., 2011, “Some Difficulties for the Problem of Unconceived Alternatives”, Philosophy of Science , 78: 875–886.
• Shapin, S. and Shaffer, S., 1985, Leviathan and the Air Pump , Princeton: Princeton University Press.
• Sklar, L., 1975, “Methodological Conservatism”, Philosophical Review , 84: 384–400.
• –––, 1981, “Do Unborn Hypotheses Have Rights?”, Pacific Philosophical Quarterly , 62: 17–29.
• –––, 1982, “Saving the Noumena”, Philosophical Topics , 13: 49–72.
• Stanford, P. K., 2001, “Refusing the Devil’s Bargain: What Kind of Underdetermination Should We Take Seriously?”, Philosophy of Science , 68: S1–S12.
• –––, 2006, Exceeding Our Grasp: Science, History, and the Problem of Unconceived Alternatives , New York: Oxford University Press.
• –––, 2010, “Getting Real: The Hypothesis of Organic Fossil Origins”, The Modern Schoolman , 87: 219–243
• Tulodziecki, D., 2012, “Epistemic Equivalence and Epistemic Incapacitation”, British Journal for the Philosophy of Science , 63: 313–328.
• –––, 2013, “Underdetermination, Methodological Practices, and Realism”, Synthese: An International Journal for Epistemology, Methodology and Philosophy of Science , 190: 3731–3750.
• Turner, D., 2005, “Local Underdetermination in Historical Science”, Philosophy of Science , 72: 209–230.
• –––, 2007, Making Prehistory: Historical Science and the Scientific Realism Debate , Cambridge: Cambridge University Press.
• van Fraassen, B., 1980, The Scientific Image , Oxford: Oxford University Press.
• Werndl, C., 2013, “On Choosing Between Deterministic and Indeterministic Models: Underdetermination and Indirect Evidence”, Synthese: An International Journal for Epistemology, Methodology and Philosophy of Science , 190: 2243–2265.

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confirmation | constructive empiricism | Duhem, Pierre | epistemology: naturalism in | feminist philosophy, interventions: epistemology and philosophy of science | Feyerabend, Paul | induction: problem of | Quine, Willard Van Orman | scientific knowledge: social dimensions of | scientific realism

Acknowledgments

I have benefited from discussing both the organization and content of this article with many people including audiences and participants at the 2009 Pittsburgh Workshop on Underdetermination and the 2009 Southern California Philosophers of Science retreat, as well as the participants in graduate seminars both at UC Irvine and Pittsburgh. Special thanks are owed to John Norton, P. D. Magnus, John Manchak, Bennett Holman, Penelope Maddy, Jeff Barrett, David Malament, John Earman, and James Woodward.

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