thought experiments and philosophical knowledge

THOUGHT EXPERIMENTS AND PHILOSOPHICALKNOWLEDGE

EDOUARD MACHERY

Abstract: While thought experiments play an important role in contemporaryanalytic philosophy, much remains unclear about thought experiments. Inparticular, it is still unclear whether the judgments elicited by thought experimentscan provide evidence for the premises of philosophical arguments. This articleargues that, if an inuential and promising view about the nature of the judg-ments elicited by thought experiments is correct, then many thought experi-ments in philosophy fail to provide any evidence for the premises of philosophicalarguments.

Keywords: thought experiments, skepticism, intuitions, philosophical expertise.

Thought experiments are a distinctive feature of contemporary analyticphilosophy, and many inuential arguments rest on premises supportedby judgments elicited by thought experiments. Just think of the Godelcase and Twin Earth in the philosophy of language, Mary the neuro-scientist and zombies in the philosophy of mind, Gettier cases inepistemology, and trolley cases or the Society of Music Lovers in ethics.Philosophers seem to assume that the judgments elicited by such thoughtexperiments have an important role to play in the growth of philosophicalknowledge.

Despite their prominence, however, much remains unclear aboutthought experiments. Of particular importance is the epistemic status ofthe judgments they elicit: Can these judgments provide evidence for thepremises of philosophical arguments? If they cant, then thought experi-ments cannot play any evidential role in philosophy, and their contri-bution to the growth of philosophical knowledge is severely limited.

In this article, I mount a defense of this kind of skepticism. Moreprecisely, I argue that an inuential and promising view about the natureof the judgments elicited by thought experiments (endorsed, e.g., in Devittforthcoming and Williamson 2007) has striking skeptical implications:many thought experiments in philosophy fail to provide any evidence forthe premises of philosophical arguments, and the kind of thought

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experiment that could provide such evidence is unlikely to be of much usefor philosophers.1

In section 1, I describe an inuential, promising view about the natureand justication of the judgments elicited by thought experiments. Insection 2, I show that this view has skeptical implications for the judgmentselicited by many thought experiments. In section 3, I examine whether onecould appeal to philosophers expertise to block these implications.

1. Thought Experiments

1.1. Two Examples

Lets start with two examples of thought experiments in recent philosophy:Kripkes Godel case and Foots and Thomsons trolley cases. According tothe versions of descriptivism Kripke criticizes in Naming and Necessity, aproper name refers to the individual that satises the description competentspeakers associate with it. By contrast, according to Kripkes causal-historicaltheory, a proper name refers to the individual this name was introduced torefer to, provided that there is a chain of uses running from the introductionof this name to its current uses. As part of the argument againstdescriptivism,2 Kripke describes a situation in which a speaker associates aproper name, Godel, with a description that is not true of the originalbearer of the name but is true of someone else, called Schmidt in the story.Descriptivist theories of reference typically entail that in this situationGodel refers to the man originally called Schmidt. But, Kripke main-tains, this is just wrong:

Suppose that Godel was not in fact the author of [Godels] theorem. A mancalled Schmidt . . . actually did the work in question. His friend Godelsomehow got hold of the manuscript and it was thereafter attributed to Godel.On the [descriptivist] view . . . when our ordinary man uses the name Godel,he really means to refer to Schmidt, because Schmidt is the unique personsatisfying the description the man who discovered the incompleteness ofarithmetic. . . . But it seems we are not. We simply are not. (Kripke 1972, 8384)

In contrast, causal-historical theories of reference are consistent withGodel referring to its original bearer because he is the person causally-historically linked with contemporary uses of the name.

Thus, the Godel case elicits the judgment that in the circumstancesdescribed by the case Godel refers to the man originally Godel. Thisjudgment is evidence that in these circumstances Godel does refer tothe man originally called Godel. That Godel refers to the man

1 I wont discuss the role and nature of thought experiments in science in this article (see,e.g., Brown 2004; Norton 2004). A more complete discussion of thought experiments wouldexamine whether and how thought experiments differ in philosophy and in science.

2 I will bracket the fact that the exact role of the Godel case in Kripkes argument againstdescriptivism is debated (Devitt forthcoming; Ichikawa, Maitra, andWeatherson forthcoming).


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originally Godel in such circumstances is the premise of the argumentagainst the common versions of descriptivism examined by Kripke.

Lets now turn to the trolley cases, focusing on Thomsons 1985 articleThe Trolley Argument. Thomson starts by discussing Foots so-calledswitch case:

Some years ago, Philippa Foot drew attention to an extraordinarily interestingproblem (Foot, 1978). Suppose you are the driver of a trolley. The trolley roundsa bend, and there come into view ahead ve track workmen who have beenrepairing the track. The track goes through a bit of valley at that point, and thesides are steep, so you must stop the trolley if you are to avoid running the vemen down. You step on the brakes, but alas they dont work. Now you suddenlysee a spur of track leading off to the right. You can turn the trolley onto it, andthus save the ve men on the straight track ahead. Unfortunately, Mrs. Foot hasarranged that there is one workman on that spur of track. He can no more getoff the track in time than the ve can, so you will kill him if you turn the trolleyonto him. Is it morally permissible for you to turn the trolley? Everyone towhom I have put this hypothetical case says, Yes, it is. (Thomson 1985, 1395)

Thomson compares Foots case with other versions of the trolley case,including the so-called footbridge case:

Consider a case . . . in which you are standing on a footbridge over the trolleytrack. You can see a trolley hurtling down the track, out of control. You turnaround to see where the trolley is headed, and there are ve workmen on thetrack where it exits form under the footbridge. What to do? Being an expert ontrolleys, you know of one certain way to stop an out-of-control trolley: Drop areally heavy weight in its path. But where to nd one? It just so happens thatstanding next to you on the footbridge is a fat man, a really fat man. He isleaning over the railing, watching the trolley; all you have to do is give him alittle shove, and over the railing he will go, onto the track in the path of thetrolley. Would it be permissible for you to do this? Everyone to whom I haveput this case says it would not be. (Thomson 1985, 1409)

The judgment that it is permissible for the driver to turn the trolley ontothe side track in the switch case is evidence that in the circumstancesdescribed by this case it is permissible for the driver to turn the trolleyonto the side track. The judgment that it is not permissible to push thelarge man in the footbridge case is evidence that in the circumstancesdescribed by this case it is not permissible to push the large man. That it ispermissible to turn the trolley onto the side track but not permissible topush the large man onto the track reveals that there is a moral differencebetween the two situations. Principles such as the Doctrine of DoubleEffect are meant to characterize this moral difference.3

3 Of course, Thomson herself is critical of the Doctrine of Double Effect.


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1.2. The Nature and Function of Thought Experiments

So, whats a thought experiment? Typically, a thought experiment describesa nonactual situation, and it invites the reader to make a judgment about anaspect of this situation (applying such concepts as REFERENCE, PERMISSI-BILITY, KNOWLEDGE, etc.). This judgment is evidence for a particular fact(e.g., that Godel refers to the man originally called Godel), and thatfact (not the act of judging itself, but the fact that makes the judgment true ifit is true) is typically used in some philosophical argument.4

Why is a judgment elicited by a thought experiment taken to provideevidence for particular facts? Presumably, for the same reason that ordinaryjudgments are often taken to provide evidence for particular facts. If I judgeof an object that it is a chair, my judgment that it is a chair is evidence that itis a chair because I am reliable at sorting chairs from nonchairs.

Providing evidence for premises of philosophical arguments is not theonly possible function of thought experiments. Thought experiments inphilosophy are sometimes merely illustrative: they are merely meant toillustrate how a theory would apply to a particular case. For instance,Davidsons (1987) swampman thought experiment may be understood asillustrating Davidsons argument rather than providing evidence for apremise of this argument. Here I will be concerned only with theevidential function of thought experiments in contemporary philosophy.

1.3. The Psychology of Thought Experiments

Although there are numerous proposals about the psychological capa-cities involved in making the judgments elicited by thought experiments,these can be classied into two fundamentally distinct types. According tothe Ordinary Judgment Proposal, the judgments elicited by thoughtexperiments are underwritten by the psychological capacities that alsounderlie the judgments we make about everyday situations. According tothis view, for instance, the same psychological capacities underwrite myjudgment that the agent described in a fake-barn case does not know thathe is seeing a barn and my judgment that, judging by his answer to thetest, one of my undergraduate students does not know what the DNaccount of explanation is. Williamson endorses this proposal about thenature of the judgments elicited by thought experiments: We should

4 Some seem to deny that the judgments themselves (viz., the acts of judging) play anyevidential role. For instance, they seem to deny that the judgment that the agent does notknow the relevant proposition in a Gettier case provides evidence for the fact that the agentdoes not know the relevant proposition. If this is really their position (which I am inclined todoubt), it is simply mind-boggling. If I am a reliable detector of knowledge in everydaycircumstances, my judgment that an undergraduate does not know what the HD account ofconrmation is provides evidence that she is indeed ignorant. Furthermore, it is hard to seewhat other kind of evidence could be put forward to support the claim that, e.g., in thesituation described by the Godel case Godel refers to Godel.


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expect the cognitive capacities used in philosophy to be cases of generalcognitive capacities used in ordinary life, perhaps trained, developed, andsystematically applied in various special ways (2007, 136).

According to the Spooky Judgment Proposal, the judgments elicitedby thought experiments and the judgments we make about everydaysituations are of a different kind, and they are underwritten by differentpsychological capacities. According to this view, for instance, my judg-ment that the agent described in a fake-barn case does not know that sheis seeing a barn and the judgment that, judging by her answer to the test,one of my undergraduate students does not know what the DN accountof explanation is are of a different kind, and they are underwritten by twodifferent psychological capacities. For instance, Sosa holds that thejudgments elicited by thought experiments such as the Gettier cases,which he calls intuitions, have very distinctive features: On myproposal, to intuit that p is to be attracted to assent simply throughentertaining that representational content. The intuition is rational if andonly if it derives from a competence, and the content is explicitly orimplicitly modal (i.e. attributes necessity or possibility) (2007, 101).5

Admittedly, the Spooky Judgment Proposal is a catch-all category.Different philosophers characterize the nature of the judgments elicitedby thought experiments and the nature of the distinctive psychologicalcapacities underwriting these differently.

In presenting the Spooky Judgment Proposal and the OrdinaryJudgment Proposal, I have alluded to the psychological capacities under-lying judgments. I have in mind the cognitive structuresnamely, thebodies of knowledge and the cognitive processes dened over theseweuse when we decide to apply a concept to a particular object or tosubsume a concept under another concept. The psychology of conceptshas much to say about the nature of these bodies of knowledge and aboutthe nature of the cognitive processes dened over these (for review, seeMurphy 2002 and Machery 2009 and 2010), but I will not discuss theimplications of this literature here (see Machery 2009, chapter 2, for somediscussion). Still, it is worth noting that the proponents of the OrdinaryJudgment Proposal sometimes have a simplistic conception of thepsychological capacities underlying judgments. It is misleading to suggestthat the application of a concept to an object (the kind of judgmentexpressed by, for example, This is a dog) is underwritten by a singlepsychological capacity. Instead, evidence suggests that this application isunderwritten by several distinct bodies of knowledge and psychologicalcapacities that are to a large extent independent of one another.6

5 I will not attempt to disentangle the knot of ideas expressed here.6 The same thing is true of the application of a concept to a substance (the kind of

judgment expressed by, e.g., This is gold), to an action (the kind of judgment expressed by,e.g., This is right), and so on.



1.4. The Epistemology of Thought Experiments

The psychology of thought experiments is philosophically relevantbecause it seems to bear on the epistemic status of the judgments elicitedby thought experimentsin particular, it seems to provide ammunitionagainst the skeptic about thought experiments. A thought experimentskeptic doubts that the judgments elicited by thought experiments provideany evidence for the premises of philosophical arguments (or at least thatthey provide sufcient evidence). Typically, the thought experimentskeptic defends his skepticism by arguing that these judgments are notsufciently reliable: the judgments are not sufciently more likely to betrue than false (for a different kind of skepticism, see Weinberg 2007).

The Ordinary Judgment Proposal seems to undermine this form ofskepticism. Because the same psychological capacities underlie everydayjudgments and the judgments elicited by thought experiments, thejudgments elicited by thought experiments seem to inherit whateverreliability everyday judgments possess. And surely everyday judgmentsare typically reliable. For instance, whatever makes my everyday judg-ments about knowledge (e.g., my judgment that one of my undergraduatestudents does not know what the DN account of explanation is) reliablealso makes the judgments about knowledge elicited by thought experi-ments in epistemology (such as my judgment that the agent in a fake-barncase does not know that a barn is in front of her) reliable. Here is anotherway to make the very same point: if the same capacities underlie everydayjudgments and the judgments elicited by thought experiments, it mightseem that one cannot challenge the reliability and thus trustworthiness ofthe latter judgments without challenging the reliability and thus trust-worthiness of all our judgmentsa price too high to pay for even themost ardent critics of thought experiments. I will call this argument theParity Defense of Thought Experiments.

Williamson, for instance, endorses this epistemological implication ofthe Ordinary Judgment Proposal. For example, he defends our judgmentsabout metaphysical possibilities on the grounds that, rst, the ordinarycognitive capacity to handle counterfactual conditionals carries with it thecognitive capacity to handle metaphysical modality and that, second, wehave an overall capacity for somewhat reliable thought about counter-factual possibilities (2007, 136).

2. Thought Experiment Skepticism

I agree with Williamsons dismissal of the Spooky Judgment Proposal. Ashe puts it, The postulation by philosophers of a special cognitivecapacity exclusive to philosophical argument or quasi-philosophicalthinking looks like a scam (2007, 136). So, in the remainder of thisarticle, I will focus on the implications of the Ordinary Judgment


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Proposal for the use of thought experiments in philosophy. Far fromundermining the skepticism about thought experiments, the OrdinaryJudgment Proposal in fact has skeptical implications: it suggests that thejudgments elicited by many philosophical thought experiments fail toprovide evidence for the premises of philosophical arguments. Thus, if theOrdinary Judgment Proposal is correct, thought experimenting (as asource of evidence for the premises of philosophical arguments) should bestringently limited in philosophy.7

2.1. Problem 1: Lack of Relevant Psychological Capacities

The rst (and least important) criticism of the Parity Defense of ThoughtExperiments begins by noting that some judgments elicited by philoso-phical thought experiments have no counterparts in everyday life. It infersthat these judgments are not underwritten by psychological capacitiesused in ordinary life, just as those expert judgments that have nocounterparts in everyday life (e.g., the judgments made by radiologistsor by archaeologists) are not underwritten by psychological capacitiesused in everyday life.8 The Parity Defense fails to uphold the epistemicstatus of this class of judgments elicited by thought experiments.Similarly, nobody would think of justifying radiologists judgments aboutcancerous nodule sites by alleging that they are underwritten by capacitiesalso used in everyday life.

Consider for instance Burges famous arthritis thought experiment (Burge1979). Burge describes an individuallets call him Oscarwho isconvinced that he has arthritis in his thigh. Burge then asks the reader toimagine a situation that is almost identical to Oscars situation. In thissecond situation, Oscars counterpart also says that he has arthritis in histhigh. The only difference between the two situations is in the languagespoken in the linguistic community of Oscars counterpart: in the Englishspoken in this second situation, arthritis applies to ailments in the anklesand to ailments in the thigh. The reader is invited to share Burges judgmentthat Oscar, but not his counterpart, has thoughts about arthritis: In thecounterfactual situation, the patient lacks someprobably allof theattitudes commonly attributed with content-clauses containing arthritis inoblique occurrence. He lacks the occurrent thoughts of beliefs that he hasarthritis in the thigh, that he has had arthritis for years, that stiffening jointsand various sorts of aches are symptoms of arthritis, that his father had

7 Note that the arguments presented in section 2 do not exclude the possibility that somethought experiments succeed in providing evidence for the premises of philosophicalarguments. But, as we will see, this kind of thought experiments is unlikely to be of greatuse to philosophers.

8 Of course, in a sense, these judgments rely on everyday cognitive competences, such ascategorization, visual recognition, and so on. Nonetheless, they do not rely on the conceptsand recognition procedures we use in everyday life.



arthritis, etc. (Burge 1979, 78). Burge concludes that what thoughts one has(viz., what concepts one possesses) depends on social facts. The kind ofjudgment elicited by Burges thought experiment (viz., the judgment thatOscar and his counterpart have different thoughts) has plausibly no counter-part in everyday life: it is dubious whether people make individuatingjudgments about thoughts. Indeed, it is plausible that lay people wouldnot know how to answer if presented with Burge-style thought experiments(for consistent evidence, see Hewson 1994; Genome and Lombrozo unpub-lished manuscript).

2.2. Problem 2: The Unreliability of Some Psychological Capacities

No doubt, some judgments elicited by thought experiments do havecounterparts in everyday life, and they are underwritten by psychologicalcapacities used in everyday life. The second criticism of the Parity Defenseasserts that we have reasons to doubt that some of these capacities arereliable even in everyday life (or that they are reliable to a sufciently highdegree for the resulting judgments to count as evidence). When this is thecase, the fact that the same psychological capacities underwrite everydayjudgments and the judgments elicited by thought experiments provides noreason to believe that the latter are reliable (or sufciently reliable), andthe Parity Defense fails to undermine the skepticism directed at philoso-phical thought experiments. Similarly, the assessment of the quality ofNew World wines by a (nonexpert) Frenchman probably relies on thesame competence he uses to assess French wines. But this fact provides noreason to think that his judgments about the quality of New World winesare correct because lay assessment of wine quality in general is mediocre(Goldstein et al. 2008).

Everyday judgments about causation in the social domain illustratethis second objection to the Parity Defense. Social psychologists haveshown that judgments about causation are systematically biased whenthey are applied to morally salient actions. For instance, Mark Alicke(1992, 2000) has shown that peoples desire to blame an agent caninuence their judgment about her causal contribution to the productionof an outcome. Consider the following vignette:

John was driving over the speed limit (about forty mph in a thirty-mph zone) inorder to get home in time to hide an anniversary present for his parents that hehad left out in the open before they could see it. As John came to anintersection, he failed to see a stop sign that was covered by a large branch.As a result, John hit a car that was coming from the other direction. He hit iton the drivers side, causing the driver multiple lacerations, a broken collarbone, and a fractured arm. John was uninjured in the accident.

Consider another vignette that is identical to the previous one except thatthe rst sentence now reads as follows:


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John was driving over the speed limit (about forty mph in a thirty-mph zone) inorder to get home in time to hide a vial of cocaine he had left out in the openbefore his parents could see it.

People tend to judge that the agent has made a greater causal contribu-tion to the outcome in the second vignette than in the rst.

More generally, peoples negative evaluation of agents, due amongother things to the biases they might harbor against minorities, inuencestheir causal judgments about the causal contribution of these agents tooutcomes. David Rose and I presented participants with one of twovignettes (unpublished data). The rst vignette was the following:

An intern is taking care of a patient in a hospital. The intern notices that thepatient is having some kidney problems. Recently, the intern read a series ofstudies about a new drug, Rascalis, that can alleviate problems like this one,and he decides to administer the drug in this case.

Before the intern can administer the drug, he needs to get the signature of thepharmacist (to conrm that the hospital has enough of the drug in stock) and thesignature of the attending doctor (to conrm that the drug is appropriate for thispatient). So he sends off requests to both the pharmacist and the attending doctor.The pharmacist, John Doughty, receives the request. After looking at the

request, John remembers hearing about the new drug. Recently, John and hisboyfriend had erotic sex. After having sex, they were lying naked in bedtogether, softly tongue kissing one another. While they were tongue kissing,Johns boyfriend was suddenly reminded about a new drug and stopped kissingJohn to tell him about it. He told John that he had recently read aboutRascalis, a fascinating new drug that can treat kidney ailments. Having beenreminded of this at the pharmacy, John checks to see that the drug is in stockand immediately signs off on the request.The attending doctor, Frank Montgomery, receives the request at the same

time and immediately realizes that there are strong reasons to refuse it.Recently, Frank was having lunch with a bright, young intern from a localuniversity, and the intern told him that although some studies show thatRascalis can help people with kidney problems, there are also a number ofstudies showing that it can have very dangerous side effects. For this reason,the hospital has a policy forbidding the use of this drug for kidney problems.Despite this policy, the doctor decides to sign off on the request.Since both signatures were received, the drug is administered to the patient.

As it happens, after receiving the drug, the patient recovers from his kidneyailment, and the drug has no adverse effects.

The second vignette was identical, except for the second and thirdparagraphs:

The pharmacist, John Doughty, receives the request. After looking at therequest, John remembers hearing about the new drug. Recently, John washaving lunch with a bright, young intern from a local university, and the interntold him that he had recently read about Rascalis, a fascinating new drug that



can treat kidney ailments. John checks to see that the drug is in stock andimmediately signs off on the request.The attending doctor, Frank Montgomery, receives the request at the same

time and immediately realizes that there are strong reasons to refuse it.Recently, Frank and his boyfriend had erotic sex. After having sex, theywere lying naked in bed together, softly tongue kissing one another. While theywere tongue kissing, Franks boyfriend was suddenly reminded about a newdrug and stopped kissing Frank to tell him about it. He told Frank that herecently read about a new drug, Rascalis, that can treat kidney ailments. Hewent on to say that although some studies show that Rascalis can help peoplewith kidney problems, there are also a number of studies showing that it canhave very dangerous side effects. For this reason, the hospital has a policyforbidding the use of this drug for kidney problems. Despite this policy, thedoctor decides to sign off on the request.

Participants were then asked the following two questions:

(1) To what extent do you think that the actions and decisions ofthe attending doctor (Frank Montgomery) caused the patientsrecovery?

(2) To what extent do you think that the actions and decisions ofthe pharmacist (John Doughty) caused the patients recovery?

In the rst vignette, the doctor was judged to be more causally responsiblefor the recovery, while in the second vignette the pharmacist was judgedto be more causally responsible. People seem to assume that theindividuals they judge to be bad (or against whom they harbor prejudices)can do no good.

The upshot should be clear: everyday causal judgments in the socialdomain are biased, and they are unlikely to be reliable (or reliable to asufcient degree for them to be treated as evidence).9 Thus, causaljudgments elicited by thought experiments provide no evidence for thepremises of philosophical arguments when the judgments bear on whetheran agent caused an outcome.

How often are the judgments elicited by thought experiments under-written by psychological capacities that are not reliable (or not reliableenough) in everyday life? It is obviously hard to know, but it is worthnoting that various philosophical views entail that such a situation is notso rare. For instance, moral error theorists (see, e.g., Mackie 1977 andJoyce 2006) hold that moral judgments are false, and eliminativist

9 One might object that the existence of such biases does not show that causal judgmentsin the social domain are unreliable (or even insufciently reliable). After all, vision suffersfrom biases, but it isnt unreliable in most circumstances. This objection, however, does nottake into account what has been learned about causal judgments in the social domain. Whenpeople are making causal judgments in the social domain, they are typically more concernedwith apportioning blame, praise, and responsibility than with getting causal relations right.


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materialists (see, e.g., Churchland 1981 and Stich 1983) hold thatascriptions of propositional attitudes are false.

2.3. Problem 3: The Atypicality of Thought Experiments

I now turn to the main criticism of the Parity Defense. To start with,whether one is able to do something or to bring about an outcome typicallydepends on the circumstances. For instance, whether one is good atshooting a handgun at a paper target depends, among other things, onhow far and how wide the target is. Ones reliability might be high for eight-inch bulls-eye targets at twenty-ve yards, but much worse for six-inchtargets at fty yards. That the reliability of a skill or capacity depends on thecircumstances in which this skill or capacity is applied is equally true of ourphysical skills and of our psychological capacities. One can be very good atmental division if the numbers are within a certain range, but quite pooroutside this range. Similarly, the reliability of a radiologists capacity torecognize cancerous nodule sites in X-rays depends on the quality of the X-rays. If the quality of an X-ray is poor, perhaps because the scanner is notfunctioning properly, the radiologist will be unreliable. I will say that thecircumstances in which a physical or psychological capacity is reliable formthe proper domain of this capacity.

If we have reason to suspect that a physical skill or a psychologicalcapacity is applied outside its proper domain, our condence in the successof this application should decrease. If we have no further information aboutthe circumstances in which the skill or capacity is applied or about how thesecircumstances impact its reliability, then, for all we know, the reliability ofthe skill or capacity in this particular application might be almost as high asit is in its proper domain, or it might be very low: that is, we have a reason tobelieve that its reliability is lower than in its proper domain, but we do notknow how low it is. In these conditions, we should be reluctant to expressmuch condence in the success of the application of the skill or capacity.

To see the point, consider the following analogy. Because we knowthat shooting accuracy decreases when people shoot at targets that aremore distant and smaller than they are used to, we should be lesscondent in the accuracy of a shooter who has been trained in shootingat twelve-inch targets at ten yards if we know that the target is smallerthan twelve inches and more distant than ten yards. If we do not knowhow distant or how small the target is or if we do not know how size anddistance affect her reliability, for all we know, the shooter might be veryunreliable (if the target is very far or is very small) or quite reliable (if, say,she is shooting at a ten-inch target at fteen yards). In these conditions,we should be reluctant to accept a bet if the odds favor the shooter hittingthe target.

This point bears on the Parity Defense. Suppose that the judgmentselicited by thought experiments and everyday judgments are underwritten



by the same psychological capacities and that these psychologicalcapacities are reliable in everyday circumstances. Even so, the judgmentselicited by thought experiments in general, or perhaps by some kinds ofthought experiment, might be less reliable (perhaps much less): thesituations described by thought experiments might be beyond the properdomains of the relevant psychological capacities. If we have a reason tosuspect that these psychological capacities are used beyond their properdomain and if we have no further information about their reliability inthese circumstances, then we should not put much stock in the resultingjudgments and, for this very reason, should not treat them as evidence.10

Suppose for instance that I am quite good at determining whether anaction is permissible in my everyday life and that, as the Ordinary JudgmentProposal would have it, my judgments about the permissibility of actions inthought experiments are underwritten by the very capacity that underliesmy everyday judgments. For all that, my judgment that in the footbridgecase it is not permissible to push the large man to stop the runaway trolleyand save ve people might still fail to provide evidence that it is notpermissible to push the large man. We might have a reason to believe thatthis type of dilemma is beyond the proper domain of our capacity to makejudgments about the permissible: while it is reliable in everyday situations,we might have a reason to believe that our capacity is less reliable whenconfronted with this type of dilemma. If we have no further informationabout its reliability in this type of dilemma, then we should not treat theresulting judgment as providing evidence for the fact that in the situationdescribed by the footbridge case it is not permissible to push the large man.

There are reasons to suspect that in many philosophical thoughtexperiments the situations described are beyond the proper domains ofthe underlying psychological capacities. Thought experiments in philo-sophy typically describe fanciful situations that are very remote from thesituations that elicit everyday judgments, and thus we cannot rely on ourmemories of tried and true past judgments in everyday situations.11

Situations are also often described in vivid terms (see, for example,Thomsons description of the trolley cases above), and their description

10 Weinberg (2007 and personal communication) doubts that attacking the reliability ofthe judgments elicited by thought experiments is a successful strategy for defending the kindof skepticism endorsed in this article because evidence fails to establish that these judgmentsare unreliable. Such evidence, however, is not required by the present argument. We shouldnot put stock in the judgments elicited by thought experiments if we have reason to believethat the situations described are beyond the proper domains of the relevant capacities and ifwe have no further information.

11 One could object that we are used to fanciful situations in, for example, science ctionor heroic fantasy novels and movies and that we regularly make judgments about them. Atan abstract level, however, the situations described in, for example, science ction novels areclearly very similar to everyday situations, and we thus have reasons to believe that theybelong to the proper domains of the relevant psychological capacities. If they are not similarin this way, then we should suspect that they do not belong to the relevant proper domains.


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contains numerous irrelevant narrative elements, features that are knownto bias judgments. Most important, thought experiments typically pullapart the features that go together in everyday life: for instance, usingphysical violence and doing more harm than good are pulled apart in thefootbridge case (see below for other examples). In such circumstances,peoples judgments tend to be less reliable because, rst, the elicitingsituations are less typical (Mccloskey and Glucksberg 1978).12 Second,they are also likely to be less reliable when they are underwritten by heuristics(Sunstein 2005). Heuristics are judgmental procedures that use the presenceof one or a few features to produce a judgment. Sometimes, these features aremerely coincidental to the truth of the judgment. For instance, Tversky andKahneman (1983) have shown that whether an individual is typical of a classis often used to judge whether he is likely to belong to this class. In everydaylife, heuristics are reliable because the features they rely on co-occur withwhatever it is that makes the resulting judgments true. This co-occurrence islikely to be disrupted when the features that go together in everyday life arepulled apart.

All these features of philosophical thought experiments should lead usto expect the elicited judgments to be less reliable than the counterpartjudgments made in everyday life. If we have no further information abouttheir reliability, the judgments elicited by thought experiments havingthese features cannot be treated as providing evidence for the premises ofphilosophical arguments, and we should be reluctant to base argumentson these judgments.

It is worth highlighting the fact that the skeptical argument againstthought experiments developed in this section does not claim that, unlessthe proponent of thought experiments can provide evidence for thereliability of the capacities underlying the judgments elicited by thoughtexperiments, we should not treat these judgments as evidence. Rather, theargument is that we have positive reasons to think that the situations

12 One could object that the judgments elicited by at least some thought experiments(e.g., Gettier cases and the footbridge version of the trolley case) do not display the featuresthat are characteristic of unreliable judgments in Mccloskey and Glucksberg (1978):disagreements among individuals and inconsistencies within individuals across occasions.In response, rst, it is worth restating that some thought experiments probably do notimpugn the reliability of the capacities underlying judgments. One would expect thesethought experiments to elicit stable, consensual judgments. Second, many thought experi-ments give rise to disagreements (e.g., Twin Earth, zombies, etc.). Finally, the stability andconsensus of judgments among philosophers should offer little solace to the proponents ofthought experiments. First, this stability and consensus might often be due to some form ofconformism: philosophers judgments about, for example, the Godel case might beinuenced by the judgments publicly stated of other (perhaps high-status) philosophers.Various contingent factors (the prestige of the inventor of the thought experiment, whether athought experiment was invented early on in a philosophical debate, etc.) might determinewhether a thought experiment elicits conformist judgments. Second, as Cummins (1998)noted, people who do not share the relevant judgments may be less likely to becomephilosophers.



described by thought experiments do not belong to the proper domains ofthe capacities underlying the judgments they elicit. That is, we have reasonsto believe that these judgments are less reliable, and if we have no furtherinformation about their reliability, we should not treat them as evidence.13

Examples abound of thought experiments displaying the features justdescribed. Lets suppose that we are good at identifying what a proper namerefers to in everyday life: we correctly judge that Barack Hussein Obamarefers to Barack Obama, and that David Lewis refers to David Lewis.Even so, it is dubious that the judgment that in the Godel case Godelrefers to the man originally called Godel provides any evidence thatGodel refers to the man originally called Godel. Situations involvingproper names associated with a single description that happens to be false ofthe original bearer of the name are probably beyond the proper domain ofour capacity to identify the reference of proper names since in everydaycircumstances many of the numerous descriptions associated with a propername tend to be true of the original bearer of the name.

It is even questionable whether the judgment usually elicited by Gettiercasesviz., the agent fails to know the relevant propositionprovidesevidence that in the circumstances described by Gettier cases the agent failsto have any knowledge. When knowledge is ascribed or denied in everydaylife, truth, justication, and the reliability of the belief-forming method gohand in hand. When people fail to know something, their beliefs aretypically false, unjustied, and the products of unreliable methods. Whenpeople know something, their beliefs are typically true, justied, and theproducts of reliable methods. By contrast, Gettier cases sever truth andjustication from the reliability of the methods of belief formation sincethey describe situations where truth comes about by luck.14 Thus, one has areason to believe that the situations described by Gettier cases are beyondthe proper domain of our everyday capacity to ascribe knowledge.

13 Not everybody will be convinced that the features of thought experiments discussed inthis article provide reasons to question the reliability of the judgments they elicit. Others willdoubt that particular thought experiments (e.g., Gettier cases) have such features. First, I amhappy to concede that more research is needed to understand which features of thoughtexperiments may undermine the reliability of the judgments they elicit. Second, the burden ofproof does not fall on the skeptics alone: proponents of thought experiments and thought-experiment skeptics should be equally concerned with the reliability of the methodsphilosophers use. In other disciplines, when the reliability of a method is questioned, criticsand users of this method attempt to determine its value. Third, I am afraid that no amount ofevidence would convince some proponents of thought experiments. People tend to have anexaggerated impression of the epistemic value of their judgments, and they are too oftenimpervious to contrary evidence: for instance, after dozens of experiments showing thesuperiority of actuarial methods (Grove et al. 2000), physicians are still reluctant to preferthem over their own clinical judgments.

14 Here the method is not the tendency to endorse ones perceptual experiences (which isa reliable method) but the use of a broken clock.


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The same basic point could be made about Putnams Twin Earththought experiment, ssion and fusion scenarios in metaphysics, mostvariants of the trolley case and various other thought experiments inethics, the truetemp case in epistemology, and many other thoughtexperiments that have been inuential in philosophy.

It is unlikely to be an accident that many thought experiments inphilosophy have some of the features described above (fanciful situationsthat pit against one another the features that co-occur in everyday life).15

Everyday judgments (about permissibility, personal identity, reference, andso on) often fail to distinguish between competing philosophical theories:these theories are all compatible with the truth of these judgments. Theproponent of the Ordinary Judgment Proposal thus faces the followingproblem. Thought experiments are likely to be most useful for philosophicalpurposes when they describe situations that differ from the situations thatelicit everyday judgments, but these situations are precisely those where theParity Defense fails. In these circumstances, that the judgments elicited bythought experiments are underwritten by the very capacities that underlieeveryday judgments provides no justication for using these judgments asevidence for premises of philosophical arguments.

It is also important to note that the fact that on occasion a real-lifesituation is similar to the situation described by a thought experiment doesnot ensure that the situation belongs to the proper domain of the relevantpsychological capacity. For instance, Williamson reports in The Philosophyof Philosophy (2007, 192) that he occasionally brings about the conditionscharacteristic of a Gettier case in the classroom, and that he then elicitsjudgments from his students (see also Williamson 2011). This fact alonedoes not ensure that the judgment elicited by a Gettier case can be used forphilosophical purposes. What is needed is some positive reason to thinkthat, despite the peculiar features of Gettier cases (see above), the situationsthey describe nonetheless belong to the proper domain of the psychologicalcapacity involved in ascribing knowledge to oneself and others.

To conclude, the proponent of the Ordinary Judgment Proposalshould recommend a skeptical attitude toward the judgments elicited bythought experiments when the situations that thought experimentsdescribe have features known to reduce the reliability of judgments.Many thought experiments in philosophy have such features, plausiblybecause the kinds of thought experiment that are most useful forphilosophers are likely to have these features. As a result, the OrdinaryJudgment Proposal leaves very little room for thought experiments tosupport the premises of philosophical arguments.

15 The use of vivid materials, however, seems to be only an accidental element of thoughtexperiments in philosophy.



2.4. Circumscribed Skepticism

The discussion in this section shows that, far from stiing skepticism, theOrdinary Judgment Proposal leads us to view with skepticism manyjudgments elicited by thought experiments. This skepticism differs fromthe types of skepticism usually considered by philosophers (contrast withWilliamson 2007, 222). Skeptical scenarios (I am a brain in a vat, an evildemon is fooling me, I am dreaming, and so on) raise a possibility that hastwo features: it is inconsistent with my actual beliefs (that I have hands, andso on), and the evidence that is non-question-beggingly available todistinguish between this possibility and my actual beliefs (for instance, myperceptual experiences) fails to support the latter over the former. In usualskeptical scenarios, no reason is presented that supports the skepticalscenario over our actual beliefs; rather, the skeptic challenges the nonskepticto show that the possible scenario she envisages is not actual. By contrast,the skepticism directed at thought experiments is supported by positivereasons: people dont apply some concepts of philosophical interest in theireveryday life, suggesting that they do not have the relevant psychologicalcapacities; empirical evidence suggests that the ordinary application of suchconcepts is biased and unreliable (or not sufciently reliable); or the thoughtexperiments describe situations that are beyond the proper domains of theunderlying psychological capacities.

One common response to skepticism is to refuse to engage with it (e.g.,Williamson 2007, 239): the nonskeptic holds that there is no reason togrant that the available evidence reduces to what the skeptic takes it to be(e.g., our perceptual experiences). While this response might be defensiblefor the usual kinds of skepticism, it is inappropriate for the skepticismabout thought experiments defended here because of the peculiarities ofthis skepticism. The thought-experiment skeptic adduces positive reasonsto doubt the judgments elicited by thought experiments. The proponentof thought experiments must explain why, appearances notwithstanding,these reasons do not undermine the reliability of the judgments elicited bythought experiments.

Finally, the skepticism defended here is satisfyingly circumscribed (seeWilliamson 2004 about this concern): it does not generalize to everydayjudgments, for the positive reasons to doubt the reliability of thejudgments elicited by many philosophical thought experiments do notcarry over to everyday judgments.

3. Philosophers Expertise

3.1. The Expertise Reply

Proponents of the Ordinary Judgment Proposal have a card up theirsleeves: they can respond that philosophers expertise undermines thearguments developed in the previous section. Even if ordinary people


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have no capacity to make judgments about, for example, propositional-attitudes individuation, philosophers might have acquired such a capa-city, and they might use it in ordinary and philosophical contexts.Similarly, radiologists have acquired the capacity to identify cancerousnodule sites in X-rays. Even if the psychological capacity underlying somekind of judgments (e.g., causal judgments in social contexts) is not reliableamong ordinary people, philosophers judgments might be reliablebecause the philosophers have thought a lot about the relevant issue(e.g., causation), because they are more cautious in making their judg-ments, and so on. Similarly, experts wine assessment is much morereliable than ordinary peoples because experts have been trained to assesswines. Even if the proper domain of a psychological capacity does notextend to the situations described by thought experiments amongordinary people, the proper domain of this capacity among philosophersmight be much broader. Thus, philosophers judgments about thereference of proper names in the Godel case and about what is permissiblein the convoluted trolley cases might be reliable. Similarly, while peopleare often good at shooting a handgun at a twelve-inch bulls-eye papertarget at fteen yards but poor when they shoot at six-inch targets at ftyyards, experts might be reliable in the latter circumstances too.

Williamson (2007, 2009, and 2011) seems to endorse this line ofreasoning (see also Ludwig 2007 and Devitt forthcoming). He writes:

Much of the evidence for cross-cultural variation in judgments on thoughtexperiments concerns verdicts by people without philosophical training. Yetphilosophy students have to learn how to apply general concepts to specicexamples with careful attention to the relevant subtleties, just as law studentshave to learn how to analyze hypothetical cases. Levels of disagreements overthought experiments seem to be signicantly lower among fully trainedphilosophers than among novices. That is another manifestation of theinuence of past experience on epistemological judgments about thoughtexperiments. (2007, 191)

Lets call this reply the Expertise Reply. The Expertise Reply is in thespirit of the Ordinary Judgment Proposal since it asserts that the samecapacities underlie the judgments elicited by thought experiments andthose elicited by everyday situations. Thought experiments elicit judg-ments that do not differ in kind from the judgments one makes ineveryday contexts. It differs from the Ordinary Judgment Proposal ininsisting that philosophers judgments about the situations described bythought experiments are more reliable than lay peoples (or perhaps thatonly the former are reliable).

There is no doubt that philosophers possess some kind of expertise,and the argument developed here against the Expertise Reply does notdepend on challenging this truism (contrast with Williamson 2009).Rather, the argument depends on the following point (for a different



line of argument, see Weinberg et al. 2010): Appealing to philosophersexpertise can stie the circumscribed skepticism put forward in section 2only if this expertise increases the reliability of the judgments philoso-phers make about the situations described in thought experiments. Butphilosophers expertise does not seem to improve the reliability of thejudgments about reference, causation, the right action, knowledge, and soon, elicited by thought experiments (or at least does not improve itsufciently for these judgments to provide evidence for the premises ofphilosophical arguments). If philosophical expertise exists, it consists insomething else.

3.2. The Princess-and-the-Pea Illusion

Are philosophers better than ordinary people at identifying causes, judgingwhether an action is permissible, determining what a proper name refers to,assessing whether an agent knows some proposition, and so on? Manyphilosophers would like to think so. For instance, Kamm writes:

Having responses to complex and unfamiliar cases requires that one see awhole complex landscape at once, rather than piecemeal. This often requiresdeep concentration. Only a few people may be able to respond to a complexcase with a rm response. . . . The princess and the pea is the fairy tale bestassociated with the method I describe: it tells of someone, despite muchinterference, who cannot ignore a slight difference that others may never sense.(1993, 8)

While Devitts views about intuitions are quite different from Kamms,Devitt agrees with Kamm about the superiority of philosophers judg-ments (for discussion, see Machery forthcoming):

[T]he normal competent speaker with even a little education does reect onlinguistic reality just as she reects on many other striking aspects of the worldshe lives in. And this education will usually provide her with the terms andconcepts of folk semantics, at least. As a result she is likely to be able to judgein a fairly immediate and unreective way what an expression refers to . . . .Still, are these referential intuitions likely to be right? I think we need to becautious in accepting them: semantics is notoriously hard and the folk are along way from being experts. Still it does seem to me that their intuitions aboutsimple situations are likely to be right. This having been said, we shouldprefer the intuitions of semanticists, usually philosophers, because they aremuch more expert (which is not to say, very expert!). (Devitt forthcoming)

Williamson suffers from the same illusion, which I will call the Princess-and-the Pea Illusion. He writes: [T]he expertise defence [what I call theExpertise Reply] does not imply that a good philosophical educationinvolves the cultivation of a mysterious sui generis faculty of rationalintuition, or anything of the kind. Rather, it is supposed to improve farmore mundane skills, such as careful attention to details in the description


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of the scenario and their potential relevance to the questions at issue(Williamson 2011).

3.3. Against the Princess-and-the-Pea Illusion

I will now present some evidence that casts doubt on the idea thatphilosophers intuitions are so reliable that they can serve as evidence forpremises of philosophical arguments.

Plausibly, if the judgments of philosophers that are elicited by thoughtexperiments are more reliable than those of lay people, then theireveryday judgments about the relevant topics (causation, responsibility,and so on) are also more reliable (assuming reasonably that lay peoplesjudgments are not perfectly reliable). That is, for instance, philosopherseveryday judgments about the permissible should be more reliable thanlay peoples. It would indeed be strange (although not inconceivable) ifthe improved reliability of philosophers judgments were limited to thesituations described by thought experiments. It is also reasonable toassume that, if philosophers judgments are more reliable than ordinarypeoples because of the expertise philosophers have acquired, the judg-ments philosophers make about their particular area of expertise shouldtend to be more reliable than the judgments of philosophers working onother areas of philosophyfor instance, ethicists judgments aboutethical matters (what is right or wrong, what is permissible, what ismorally required, and so on) should be more reliable than metaphysi-cians. It is also reasonable (although not uncontroversialsee below) toassume that, if ethicists judgments about ethical matters are more reliablethan other philosophers, then ethicists actions should be better thanother philosophers, since ethicists judgments have practical signicance.

In recent years, Eric Schwitzgebel has accumulated a large body ofevidence suggesting that ethicists do not behave better than other philoso-phers. Moral philosophers are 50 percent more likely to borrow bookspermanently from libraries than other philosophers (Schwitzgebel 2009).That is, moral philosophers are 50 percent more likely to steal books fromlibraries! Moral philosophers are also not more likely to abide by elemen-tary norms of politeness (such as replying to e-mail or behaving properly inconferences) than other philosophers (Schwitzgebel forthcoming). Finally,moral philosophers, including political philosophers, are not more likely tovote than other philosophers (Schwitzgebel and Rust 2010). Unsurprisingly,philosophers tend to think that ethicists do not behave better than otherphilosophers (Schwitzgebel and Rust 2009)!

I view this growing body of ndings as indirect evidence that ethicistsjudgments about ethical matters are not more reliable than otherphilosophers, which casts doubt on the idea that philosophical expertiseimproves the reliability of the judgments elicited by thought experiments.Of course, one could challenge this interpretation of Schwitzgebels



ndings on various grounds. The connection between ethicists actionsand the reliability of the judgments elicited by thought experiments isadmittedly indirect. Furthermore, the quality of philosophers judgmentsneed not be reected in their actions. After all, moral philosophers mightfail to act on their enlightened judgments for a variety of reasons,including weakness of the will, failure to pay attention to their ownjudgments when they act, and so on.

There is, however, some more direct evidence challenging the ExpertiseReply. Schwitzgebel and Cushman (unpublished manuscript) gave parti-cipants both the bystander and footbridge trolley cases in two differentorders, and they examined whether the order of presentation inuencedlay peoples and philosophers judgments. You would think that, if thejudgments of philosophers that are elicited by thought experiments aremore reliable, they would be less inuenced by the order of presentation.It turns out, however, that philosophers, including ethicists, are asinuenced as lay people by the order of the cases.

You would also think that, if the judgments of philosophers that areelicited by thought experiments are more reliable, philosophers theore-tical commitments would not have a large inuence on their judgments.To examine this question, I gave the Godel case to linguists andphilosophers of language (Machery forthcoming; for further discussionof the relation between expertise and linguistic intuitions, see Culbertsonand Gross 2009; Machery and Stich forthcoming). It turns out that thejudgments of linguists and philosophers of language about the referenceto Godel in this case are inuenced by their disciplinary training:linguists who work in elds that highlight the descriptions associated withwords (sociolinguistics, historical linguistics, anthropological linguistics)are less likely to have Kripkean intuitions than those linguists who arelikely to have read Naming and Necessity during their training (semanti-cists and philosophers of language).16

Current evidence tentatively suggests that the Princess-and-the-PeaIllusion is just thatan illusion. Admittedly, the ndings reviewed in thissection fall short of establishing beyond doubt that philosophers ex-pertise does not consist in part in an increased reliability of theirjudgments about causation, the permissible, and so on. However, theycast sufcient doubt on this idea to prevent philosophers from simplygesturing at their expertise when they attempt to undermine the skepti-cism about thought experiments. Philosophers who want the justicationof thought experiments to hang on the contribution of their expertise tothe reliability of their judgments should put up or shut up: evidence iscalled for.

16 Or perhaps the former disciplines attract more students with descriptivist intuitionsand the latter more students with Kripkean intuitions!


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3.4. What Does Philosophers Expertise Consist In?

Philosophers often make (occasionally pompous) claims about the natureof their expertise, and they are fond of supporting them with anecdotes.But the truth is we know very little about the nature of philosophersexpertiseviz., about what philosophers are distinctively good at, aboutwhether and how this expertise is acquired, and so on. The reason for thisignorance is that there have been very few empirical, systematic studies ofthese questions: the psychology of philosophy remains underdeveloped.

As we have seen, evidence suggests that expertise might not consist in acapacity to make more reliable judgments. On the other hand, there is nodoubt that philosophers acquire some expertise. What does it consist in?In recent work, Livengood, Sytsma, Feltz, Scheines, and Machery (2010)have started to examine what we call the philosophical temperament.By this we mean the characteristics that are distinctive of philosophers.Participants were presented with the Cognitive Reection Test throughthe Philosophical Personality website (philosophicalpersonality.com).The idea behind the Cognitive Reection Test is to present participantswith questions that have intuitive answers that are incorrect. To arrive atthe correct answer requires participants to move beyond the answer thatinitially comes to mind and to consciously reect on the problem instead.The Cognitive Reection Test consists of three questions of this sort:

(1) A bat and a ball cost $1.10 in total. The bat costs $1.00 more than the ball.How much does the ball cost? _______ cents.

(2) If it takes 5 machines 5 minutes to make 5 widgets, how long would it take100 machines to make 100 widgets? _______ minutes.

(3) In a lake, there is a patch of lily pads. Every day, the patch doubles in size.If it takes 48 days for the patch to cover the entire lake, how long would it takefor the patch to cover half of the lake? _______ days. (Frederick 2005, 27)

We collected data on 4,472 participants, 823 of whom reported having atleast some philosophical training. We found that training in philosophypositively correlates with Cognitive Reection Test score even whencontrolling for education level. Thus, if we consider each level ofeducation separately (with the exception of participants with a vocationalor trade degree), the mean score for participants with some training inphilosophy is higher than for those without training in philosophy.

These ndings cast light on an important characteristic of the philo-sophical temperament: philosophers are less likely to blindly accept theirintuitions and more likely to submit those intuitions to scrutiny. Philos-ophers ponder; they question what spontaneously seems to be the case;they readily take a skeptical eye toward how things seem to them.Philosophical expertise is thus real and distinctive (more on this inLivengood et al. 2010). But, so far as we know, it does not consist in



being more reliable at judging whether something is a cause, what aproper name refers to, what is permissible in specic situations, and so on.

Conclusion

The argument developed in this article does not support an unconditionalform of skepticism toward all thought experiments in philosophy. Rather, itsupports the following conditional skeptical claim about many (but plausiblynot all) philosophical thought experiments: if the inuential, reasonable viewthat the judgments elicited by thought experiments and everyday judgmentsare underwritten by the same psychological capacities is correct, then manythought experiments (and in any case the kind of thought experiment that isplausibly most needed to decide between competing philosophical theories)cannot be used to support the premises of philosophical arguments. Thisskepticism, which is not abated by the appeal to philosophers expertise, issatisfyingly circumscribed: fortunately, it does not breed any untowardskepticism against ordinary judgments.

Department of History and Philosophy of ScienceUniversity of Pittsburgh1017CLPittsburgh, PA [email protected]

Acknowledgments

I would like to thank Armen Marsoobian for organizing the conferenceThe Future of Philosophy: Metaphilosophical Directions for the Twenty-First Century. I would also like to thank Joshua Alexander, JoachimHorvath, Eric Schwitzgebel, and Jonathan Weinberg for their commentson previous versions of this article.

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