Published online by Cambridge University Press: 01 January 2020
The course of my experience is quite consistent with the hypothesis that it is being produced by a mad scientist who is feeding into my sensory receptors entirely delusive stimuli. Indeed, I could at this very moment be nothing more than a brain floating in a vat of nutrients, my nerve ends linked up to some infernal apparatus by means of which my unknown deceiver induces in me utterly erroneous beliefs about the world.
So begins a familiar line of thought which dramatizes an equally familiar sceptical problem about the relation between our experiences and the world. However, Hilary Putnam has recently offered a marvellously ambitious argument which is intended to kill stone-dead the philosophical fantasy that we might be deluded brains in a vat.
1 See the opening chapter of Putnam, Hilary Reason, Truth and History (Cambridge: Cambridge University Press 1981).CrossRefGoogle Scholar All quotations are from this chapter.
2 Cf. Dennett's, Daniel fantasy in his superb entertainment ‘Where am I?’ in his Brainstorms (Montgomery, VT: Bradford Books 1978).Google Scholar
3 To keep things simple, I will adopt Putnam's phrasing here: if you think (correctly in my view) that there are further problems lurking here, then so much the worse for Putnam's original argument.
4 Those with whom I have discussed Putnam's argument seem equally divided into two camps — one holding that Putnam is obviously right, the other that he is obviously wrong. I can't agree that the matter is obvious either way, for (as I have suggested above) it is not clear how Putnam's argument is properly to be understood. But I can now offer a diagnosis of the dissent: Those who side with Putnam have seen that he points to reasons for thinking that the speculation that we are radically deluded brains in this-worldly vats is self-defeating. Those who side against Putnam have seen that the role of fantasies about brains-in-vats is to provide a model of an epistemic predicament, and it cannot be ruled out that we are in such a predicament merely by showing that we are not actually brains-invats of a this-worldly sort.
5 See e.g. Putnam, Hilary ‘Realism and Reason’ in his Meaning and the Moral Sciences (London: Routledge and Kegan Paul 1978).Google Scholar