2 Putnam, H. Reason, Truth and History (New York: Cambridge University Press 1981), ch.1CrossRefGoogle Scholar

3 Ibid., 6. This point is stressed in Davies, D. ‘Putnam's Brain-Teaser,’ Canadian Journal of Philosophy 25 (1995), 224–7CrossRefGoogle Scholar, and in Hymers, M. Philosophy and Its Epistemic Neuroses (Boulder, CO: Westview 2000), ch. 1.Google Scholar

4 To simplify the presentation, the paper will typically focus on the types of claims that we can make. Nevertheless, the point should be understood as extending to the thoughts expressed by those claims. The relevant issues deal with the limitations on what we can think about as much as they do with what we can coherently talk about.

5 Reason, Truth and History, 5-6

6 Ibid., 14. See also, ‘Although the people in that possible world can think and “say” any words we can think and say, they cannot (I claim) refer to what we can refer to. In particular, they cannot think or say that they are brains in a vat (even by thinking “we are brains in a vat”)’ (ibid., 8).

7 Ibid. See also: ‘It follows that if … we are really brains in a vat, then what we now mean by “we are brains in a vat” is that we are brains in a vat in the image or something of that kind (if we mean anything at all). But part of the hypothesis that we are brains in a vat is that we aren't brains in a vat in the image …. So, if we are brains in a vat, the sentence “We are brains in a vat” says something false (if it says anything). In short, if we are brains in a vat, then “We are brains in a vat” is false. So it is (necessarily) false’ (ibid., 15).

8 For a discussion of this, see Brueckner, A. ‘Brains in a Vat,’ Journal of Philosophy 84 (1986), 152Google Scholar.

9 I am here following Wright, C. ‘On Putnam's Proof that We Are Not Brains in a Vat,’ Clark, P. and Hale, B. eds., Reading Putnam (Cambridge: Blackwell 1994), 224Google Scholar, since Putnam himself seems to endorse this reconstruction (Putnam, H. ‘Comments and Replies,’ Clark and Hale, eds., 284CrossRefGoogle Scholar). In any case, the objections considered below should be locatable in any of the many acceptable formulations of Putnam's argument available.

10 For the best known exposition of this line, see Brueckner, ‘Brains in a Vat.’

11 ‘I can conclude … that I am a normal human being rather than a BIV … only if I can assume that I mean by “I may be a BIV” what normal human beings mean by it. But I am entitled to that assumption only if I am entitled to assume that I am a normal human being speaking English rather than a BIV speaking vat-English. This must be shown by an anti-skeptical argument, not assumed in advance’ (Brueckner, ‘Brains in a Vat,’ 103)Google Scholar.

12 The connection between externalism and this possibility is made very vivid in the discussion of the ‘Swampman’ in Davidson, D. ‘Knowing One's Own Mind,’ Ludlow, P. and Martin, N. eds., Externalism and Self-Knowledge (Stanford: CLSI Publications 1998)Google Scholar. Putnam discusses a related possibility in Reason, Truth and History, 17. The possibility of externalist anti-skeptical arguments backfiring in this way is discussed by Brueckner, ‘Brains in a Vat,’ 159Google Scholar; Falvey, and Owens, ‘Externalism, Self-Knowledge, and Skepticism,’ Philosophical Review 103 (1994) 107–37, at 126CrossRefGoogle Scholar; Klein, P. ‘Radical Interpretation and Global Skepticism,’ LePore, ed., Truth and Interpretation (Oxford: Blackwell 1986), 385Google Scholar; and Stich, S. ‘Might Man Be an Irrational Animal?’ Kornblith, H. ed., Naturalizing Epistemology (Cambridge: The MIT Press 1994),356.Google Scholar

13 See, for instance, Brueckner, ‘Brains in a Vat’; Nagel, T. The View from Nowhere (New York: Oxford University Press 1986)Google Scholar; Falvey and Owens; Wright, ‘On Putnam's Proof’; Davies, ‘Putnam's Brain-Teaser’; Forbes, G. ‘Realism and Skepticism: Brains in a Vat Revisited,’ Journal of Philosophy 92 (1995)CrossRefGoogle Scholar; Ebbs, G. Rule Following and Realism (Cambridge: Harvard University Press 1997)Google Scholar; Noonan, H. ‘Reflections on Putnam, Wright, and Brains in Vats,’ Analysis 58 (1998)CrossRefGoogle Scholar; Sawyer, S. ‘My Language Disquotes,’ Analysis 59 (1999)CrossRefGoogle Scholar; Ludlow and Martin; and the numerous papers cited therein.

14 After all, most people (including Putnam himself: Reason, Truth and History, 7) typically do feel that there must be something ultimately wrong with Putnam's argument when it is first presented to them. (Or at least that is my experience with students when they are presented with the argument, and with most of my colleagues with whom I have discussed it.) Their intuition is that there must be something wrong with the argument, even if they cannot pin down precisely what that something might be.

15 For a discussion of some of these, see Stroud, B. The Significance of Philosophical Skepticism (New York: Oxford University Press 1984)CrossRefGoogle Scholar.

16 See Falvey and Owens; McGinn, C. ‘Radical Interpretation and Epistemology,’ LePore, ed.; and Williams, M. Unnatural Doubts (Cambridge: BlackwellGoogle Scholar 1991), xiv, for claims of this sort. However, I will ultimately argue that a commitment to ‘semantic externalism’ is perfectly compatible with the hypothesis's intelligibility, and thus that no reductio of semantic externalism is in the offing.

17 I should note that this case departs from Putnam's example slightly since it allows that there are other conscious creatures outside of the vat. Nothing, however, should turn on this, since the creatures outside of the vat are taken to have nothing to do with the vat in which the brain sits and the virtual world generated by the computer.

18 A point that should be familiar from Putnam's own discussions of the feasibility of purely causal accounts of reference. (See, for instance, Reason, Truth and History, 53.)

19 I doubt that terms like ‘natural kind’ or ‘functional kind’ themselves pick out ‘semantically natural kinds,’ and so these suggestions are not meant to be capture of how all such kind terms should be characterized.

20 Putnam is less than clear about what these ‘virtual vats’ should themselves be understood to be. Vats in the image, electronic impulses, and program features have all been suggested by Putnam (Reason, Truth and History, 14), Davidson (according to Rorty, R. ‘Pragmatism, Davidson and Truth,’ Objectivity, Relativism and Truth [New York: Cambridge University Press 1991])Google Scholar, and others. I will try not to take a stand on this issue, and will just treat ‘virtual vats’ to pick out whatever is causally responsible for the brain's ‘vat utterances.’ Consequently, the ‘virtual vats’ should not be understood as in any way fictional in the way that we think of unicorns as fictional, since, whatever they are, they have causes and effects.

21 One might question this use of ‘real vat’ and thus Putnam's claim that ‘the use of “vat” in vat-English has no causal connection to real vats’ (Reason, Truth and History, 14). Both may seem to beg the question at hand by assuming that the vats in the image could not be ‘real.’ On the other hand, one might try to preserve Putnam's claim by arguing that ‘real’ could be used as a comparative term picking out a type of vat, and something that was not a ‘real’ vat could still ‘truly’ be a vat. On the various uses of ‘real’ see Austin, J.L. Sense and Sensibilia (Oxford: Oxford University Press 1962), ch. 7.Google Scholar

22 For ease of exposition, assume that we are not brains in vats, and that ‘physical’ refers to this environment, while ‘virtual’ is virtual relative to this environment.

23 Of course, one might try to argue that the categories of P- and V- Vats are somehow more ‘natural’ than that of C-vats, and that the initial samples only ‘project’ to such ‘natural’ properties. See, for instance, Lewis, D. ‘New Work for a Theory of Universals,’ Australasian Journal of Philosophy 61 (1983)CrossRefGoogle Scholar and ‘Putnam's Paradox,’ Australasian Journal of Philosophy 62 (1984). However, such a line could hardly be appealed to by Putnam, since such an interest-independent ‘ranking’ of properties is one of the characteristics of Metaphysical Realism he is most anxious to reject. One of the main themes in Reason, Truth and History is precisely that there are no such ‘objective’ degrees of similarity.

24 Note that Putnam assumes, in ‘Realism and Reason,’ Meaning and the Moral Sciences (Boston: Routledge & Kegan Paul 1978), 127, that the metaphysical realist would describe the brain in the vat as referring toP-Vats rather than C-Vats by ‘vat.’

25 The issue of how to understand premise (ii) is actually more complex that this. One might argue that all that Putnam's argument requires is that the phrase ‘brains in a vat’ have different extensions in English and Vat-English. (Indeed, Wright suggests something like this in ‘On Putnam's Proof,’ 221-3.) Consequently, as long as the reference of ‘vat’ in English was the set of P-Vats, then the argument would go through whether the Vat English expression referred to either C or V-Vats. However, if one takes this line (and I would argue that establishing that the English expression picks out just P-vats is a non-trivial task) the problem reemerges in terms of the question of determining what the referent of ‘vat-English’ is supposed to be. If ‘vat-English’ is simply the language spoken by any brains in vats that I would encounter in my environment, then the argument is not an interesting one, since there was never a worry about whether I was a brain in one of the vats in my current environment. On the other hand, if ‘Vat English’ is just a general term for English-like languages spoken by anything my expression ‘brain in a vat’ can truly apply to, it is less clear that it picks out a single language that can be identified with the version of English that would be spoken by any brains in vats found in this environment.

26 Putnam, H. ‘The Meaning of “Meaning,”’ Mind, Language and Reality (New York: Cambridge University Press 1975), 232CrossRefGoogle Scholar

27 After all, ‘vat’ would seem to mean the same thing in English and its Earth2 counterpart, even if the term was applied to an entirely different set of objects on Earth2.

28 Putnam, ‘The Meaning of “Meaning,”’ 239. This emphasis on our interests separates him, to his credit, from Devitt, M. Designation (New York: Columbia University Press 1980)Google Scholar and D. Lewis, ‘New Work’ and ‘Putnam's Paradoxes.’

29 Cross-environmental relations replacing cross-world ones here, since the same object could have different interactional properties in different environments within the same world.

30 The sort of similarity has more to do with the way the subjects involved experience (or would experience) the interaction. (Hence the term ‘interactional kind’ might also go by ‘experiential kind.’) As discussed below, the types of interaction might ‘objectively’ be quite different, since, for instance, what goes on when a non-virtual body kicks a non-virtual vat is significantly different from what goes on when a virtual body ‘kicks’ a virtual vat. Nevertheless, these two different relations are experienced by the subjects involved in a way that would naturally strike them as relevantly similar.

31 There are, of course, some ‘skeptical’ hypotheses that might still be self-refuting. For instance, the claim ‘I have always been a brain in a vat on the dark side of the moon’ may be self-refuting. Even if a brain in the vat could talk about our moon as ‘a moon,’ when it uses the term ‘the moon’ it refers to something in the image, not in our world. Much the same could be said of the hypothesis ‘I have always been a brain in a vat sitting in Hilary Putnam's basement.’ Such hypotheses make reference to certain particulars in our environment and thus require names for their formulation. However, the interest of these skeptical hypotheses is obscure to me. Furthermore, there may very well be future experience (discovering massive and constant switching, etc.) that would lead us to conclude that our ‘proper names’ actually were multi-realizable kind terms.

32 Some seem to think that the term ‘functional kind’ should only be used this way; hence my preference for ‘interactional’ kind for the more flexible class of terms. There is, I should note, nothing about the more restrictive account's reference to an actual environment that makes it more in keeping with Putnam's ‘indexical’ account of meaning than the first. Each type of term allows that the objects experienced in the initial environment help determine the reference, the disagreement is just over which type of sortal these initial samples should be understood in terms of.

33 Furthermore, such an understanding of functional kinds would seem to miss out on how we understand even such basic functional kinds such as ‘heart.’ While human hearts and mouse hearts play similar roles in their respective environments, they could not, to put it mildly, play their roles adequately if their environments were switched. Such an interpretation would also require that the meaning of ‘phone’ has changed over the last 20 years, since many phones we now use (cell phones in particular) would not be able to function in a remote or past environment where there were no satellites to support them. A less environmentally restrictive account of functional kinds, on the other hand, could easily explains why we are entitled to consider cell phones to be a type of phone. These considerations are hardly conclusive, but as will soon become dear, for the purposes of the current argument, the cross-environmental interpretation of ‘vat’ need only be established as possibly correct to cause problems for Putnam's argument.

34 For a discussion of such cases, see Putnam, H. The Many Faces of Realism (LaSalle: Open Court 1987), 5–6Google Scholar; Thompson, E. Color Vision (New York: Routledge 1995)Google Scholar; Lakoff, G. and Johnson, M. Philosophy in the Flesh (New York: Basic Books 1999)Google Scholar. Furthermore, there is now considerable evidence that classification is often not carried out in terms of categories defined in terms of shared sets of properties; see Rosch, E. ‘Family Resemblances: Studies in the Internal Structure of Categories,’ Cognitive Psychology 7 (1975)CrossRefGoogle Scholar, and Lakoff, G. Women, Fire and Dangerous Things (Chicago: University of Chicago Press 1987)CrossRefGoogle Scholar. I do not have the space to pursue this point here, but if one accepts such ‘prototype driven’ accounts of concepts and categories, it would be even easier to defend the claim that a term like ‘vat’ could be truly applied within the new environment. Much the same could be said of the more ‘open textured’ account of concepts defended in, for instance, Travis, C. The Use of Sense (New York: Oxford University Press 1989)Google Scholar and Jackman, H. ‘Semantic Norms and Temporal Externalism,’ PhD Diss (University of Pittsburgh 1996)Google Scholar and ‘We Live Forwards but Understand Backwards: Linguistic Practices and Future Behavior,’ Pacific Philosophical Quarterly 80 (1999).

35 This may require a fairly stable type of switching between the environments, ‘virtual vats’ only being encountered when one is ‘in’ one's ‘virtual body,’ etc. The stability of such kind terms is thus dependent on some fairly contingent features of our situation. This is, however, arguably a feature of much of our language. For some suggestive discussions on this theme, see Wittgenstein, L. Philosophical Investigations, 3rd ed. (Oxford: Blackwell 1953)Google Scholar, and Austin, J.L. Philosophical Papers (Oxford: Oxford University Press 1961)Google Scholar.

36 Though it is far from clear that it shouldn't. After all, if we were to enter into the vat's virtual world, we probably would use regular English words to describe the ‘virtual’ phones, cars, and vats that we experienced. This raises the question of why we shouldn't simply understand these words in terms of the experienced similarities that lead us to apply them cross-environmentally. (Once again, for ease of exposition, I'm assuming here that we are not brains in vats.)

37 Putnam, H. ‘Comments and Replies,’ 287Google Scholar

38 For Putnam's use of these terms for any account that would allow the brains in the vat to refer to vats with ‘vat,’ see Reason, Truth and History, 3, 5, 15, 16, and ‘Comments and Replies,’ 287.

39 If one of them were to say ‘we might all be brains in a vat,’ another could correctly reply, ‘we couldn't be, since all the nutrient fluid would flow out of the holes.’

40 This is why the analysis should not be viewed as ‘phenomenalistic’ (though a phenomenalistic analysis of the terms in one's language might seem more plausible if one didn't have a single experiential environment). The cause of the phenomenon still helps determine the term's extension. Some have argued that non-natural kinds should not be viewed as ‘indexical’ in this way— Schwartz, S. ‘Putnam on Artifacts,’ Philosophical Review 87 (1978)CrossRefGoogle Scholar and ‘Natural Kinds and Nominal Kinds,’ Mind 89 (1980); and Devitt, M. and Sterelny, K. Language and Reality (Oxford: Blackwell 1987)Google Scholar —and that the extensions of such ‘nominal kinds’ are ‘determined by an analytical specification of superficial features such as phenomenal properties, and/ or form, function, or origin’ (Schwartz, ‘Natural Kinds and Nominal Kinds,’ 182). Such accounts, however, must assume that we (or at least some member of our community) can know a priori what the relevant functional or formal properties are, and there is no reason to think that this must be (even if it often is) the case. I won't defend this last claim at length here, but the point is developed in Kornblith, H. ‘Referring to Artifacts,’ Philosophical Review 89 (1980)CrossRefGoogle Scholar, and H. Jackman, ‘Semantic Norms.’

41 Which is more than just assuming that we won't experience a de-vatting. The relevant dispositions are present as long as de-vatting is possible.

42 Precisely what sort of kind it may be is less clear. It may, for instance, be an artifact kind term, whose deliberate construction to play a certain role in our lives is essential to its being a member of the kind. In such a case, there could be no ‘naturally occurring’ vats. Treating ‘vat’ as a term for an artifact kind rather than for the more generic sort of interactional kind suggested above would still, however, allow the term to be applied cross-environmentally.

43 This example is, of course, an adaptation of Putnam's own discussion of ‘pencil’ (‘The Meaning of “Meaning,”’ 242-3).

44 Or one could take the more extreme position that such a case would amount to our discovering that there were no, and never had been any, vats. For something like this view, see Katz, J. ‘Logic and Language: An Examination of Recent Criticisms of Intentionalism,’ Gunderson, K. ed., Minnesota Studies in the Philosophy of Science VII (Minneapolis: University of Minnesota Press 1975)Google Scholar. However, Putnam himself clearly seems unsympathetic with this approach to such cases (see ‘The Meaning of “Meaning”’). More plausibly, one might think that the term should be understood as indeterminate between the natural and the interactional kind in the way that a term like ‘dog’ might be understood as indeterminate between an ‘evolutionary’ and a ‘genetic’ understanding. The latter of these would allow a ‘synthetic dog’ which had no genealogical connection to our dogs, but an identical physical and genetic make-up, to be a dog, while the former would not. See Putnam, H. ‘Aristotle After Wittgenstein,’ Words and Life (Cambridge: Harvard University Press 1994), 76–7.Google Scholar

45 The echo from James, W. Pragmatism (1907; Cambridge: Harvard University Press 1975), 106Google Scholar, is found in Putnam's work as well - see Putnam, H. Pragmatism, An Open Question (Cambridge: Blackwell 1995)Google Scholar, S—and its relation to some of the views presented here are developed further in Jackman, H. ‘James' Pragmatic Account of Intentionality and Truth,’ Transactions of the C.S. Peirce Society 34 (1998)Google Scholar.

46 One can see this in recent definitions of ‘life,’ where the properties essential to the kind are all of a functional/interactional sort that can be shared by various ‘objects’ found within the running of an appropriately programmed computer. See, for instance, the discussion of ‘artificial life’ in Turkle, S. Life on the Screen (New York: Simon and Schuster 1995)Google Scholar. Furthermore, one might argue that the experience of ‘devatting’ would lead us to reshape our conception of the ‘physical’ in a way that would allow ‘natural kind’ terms, and even the term ‘physical’ itself, to apply cross-environmentally.

47 See, for instance, his discussion of ‘cat,’ ‘energy,’ and ‘pencil’ in Putnam, H. ‘It Ain't Necessarily So,’ Mathematics, Matter and Method (New York: Cambridge University Press 1975)Google Scholar, ‘The Analytic and the Synthetic,’ Mind, Language and Reality, and ‘The Meaning of “Meaning.”’

48 Indeed, our fallibility with respect so such questions has been evident in philosophic discourse from Socrates down to the present day.

49 Once again, this is assuming that ‘brain in a vat’ stands for the second scenario Putnam describes, which does not involve recent envatting or ‘switches’ between the ‘real’ and ‘virtual’ environments.

50 Of course, while the view makes room for the assurance that most of our assertions are true, by allowing that we cannot tell whether or not we are a brain in a vat, it may leave us open to a type of skepticism about our knowledge of the content of such true assertions. If it turns out that we don't, on such a view, know what we are saying, then it would be hard to claim that any of these true assertions amount to knowledge. There thus seems to be room for some sorts of skepticism here, even if it is not of the traditional ‘all of my beliefs might be false’ variety. (For a useful discussion of these issues, see Hymers.) Fortunately, I think that such worries about our knowledge of the content of our assertions and thoughts can be addressed. I have no space to do so here, but see Jackman, H. ‘Semantic Norms,’ ‘Deference and Self-Knowledge,’ Southwest Philosophy Review 16 (2000)CrossRefGoogle Scholar, and ‘Ordinary Language, Conventionalism, and A Priori Knowledge,’ Dialectica (forthcoming); for a related discussion, see D. Davidson, ‘A Coherence Theory of Truth and Knowledge,’ LePore, ed., and ‘Knowing One's Own Mind.’

51 Reason, Truth and History, 6

52 Reason, Truth and History, 49. For a discussion of this, see, once again, Davies, ‘Putnam's Brain-Teaser’ and Hymers.

53 Wright, ‘On Putnam's Proof,’ 239-40Google Scholar. See also Forbes, ‘Realism and Skepticism.’ The same sort of intuition, though more explicitly tied to the traditional problem of skepticism, is expressed in Nagel, 73.

54 ‘Comments and Replies,’ 287-8

55 Putnam seems to suggest that a future de-vatting could only be relevant by allowing the brain in the vat access to descriptions such as ‘the things I will refer to as “vats” at such and such a future time’ (Reason, Truth and History, 16). In much the same way, Putnam claims that the brain in a vat hypothesis would be a coherent one if it predicted a de-vatting some time in the future (Reason, Truth and History, 131). However, even the potential for de-vatting, whether it is actualized or not, is relevant to the interpretation of one's terms. Even if the brain is not de-vatted, it is still disposed to respond to its de-vatting in a particular way, and these dispositions help constitute what it should be interpreted as meaning by its terms.

56 Reason, Truth and History, 55. Or at least the Putnam of Reason, Truth and History did. Putnam's views on the topic of truth have changed since then. See Putnam, H. Representation and Reality (Cambridge: The MIT Press 1988)Google Scholar and ‘Sense, Nonsense, and the Senses: An lnquiry into the Powers of the Human Mind,'JournalofPhilosophy 91 (1994).

57 As Horgan puts it, the relevant sense of idealization must also include an idealization of the cognizer's epistemic vantage point, Horgan, T. ‘Metaphysical Realism and Psychologistic Semantics,’ Erkenntnis 34 (1991), 303CrossRefGoogle Scholar. That such a qualification is implicit in Putnam's own view of truth is suggested in Davies, D. ‘Why One Shouldn't Make an Example of a Brain in a Vat,’ Analysis 57 (1997)Google Scholar, and Putnam makes it more explicit in Putnam, H. Representation and Reality, ‘Reply to Terry Horgan,’ Erkenntnis 34 (1991)Google Scholar, and ‘Sense, Nonsense, and the Senses.’ For a discussion of this aspect of Putnam's recent writings on truth, see Wright, C. ‘Truth as Sort of Epistemic: Putnam's Peregrinations,’ Journal of Philosophy 97 (2000)Google Scholar.

58 ‘Realism and Reason,’ 127 (Italics, as elsewhere, are Putnam's). Note that not only are the unexperienced vats outside the vat referred to as ‘noumenal,’ but it is also assumed that the hypothesis requires that vats in the image do not fall within the extension of ‘vat.’

59 Exactly how Kant's distinction between appearances and things in themselves should be understood is a notoriously difficult topic. Nevertheless, it seems fairly certain that, whatever the proper understanding of Kant's distinction between the noumena and phenomena is, it will be significantly different from the relation between experiences within the vat and experience of the world outside of it. For instance, the noumena are not distinct objects from the phenomena that could, in fact, eventually be objects of experience themselves.

60 Say, the ‘de-vatting’ also occurs through some ‘cosmic’ coincidence. H the first coincidence is ‘physically possible’ then it should seem as if the second would be as well There should, then, be no problem tying such potential experiences to idealized, if not actual, inquiry.

61 No commitment need be taken on here about the truth-value of this conditional's antecedent.