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Question How do we know we are not a computer program? In other words, some kind of video game? I know of the the brain in a vat argument but why suppose we have a brain at all? What if our "mind" is a computer only running a "human program" or some such thing? What if all sensation is just data in a computer and all "WE" are is just data in a computer? Any problems with this argument?

Accepted:
November 29, 2007

Comments

It's not obvious what the argument is here. Are we trying to argue that we actually are just avatars in a computer simulation? If so, then the argument seems pretty weak. Are we trying to argue that we don't know that we're not avatars in a computer simulation? Then., again, one wants to know what the argument actually is. It seems to be something like: We can't absolutely rule out that we're not avatars, etc, etc. And if so, then, yes, I agree that Putnam's brain-in-a-vat argument is actually pretty hopeless. But my own view, for what it's worth, is that the BIV argument doesn't actually have anything to do with skepticism. (I think it has to do with metaphysical realism, a very different topic.) But the deeper question, I think, is whether knowing that p actually requires being able to rule out the bare possibility that not-p, and not everyone would agree that it does, especially where skeptical scenarios are concerned.

Have a peek, for instance, at Jim Pryor's paper "The Skeptic and the Dogmatist" or, for that matter, at G.E. Moore's paper "A Defense of Common Sense". Moore claims that he knows that he has two hands and, since it follows from the fact that he has hands that he is not an avatar---avatars don't have hands---it follows that he knows that he isn't an avatar. He agrees, to be sure, that he can't prove that he has hands---you can't prove anything, except in mathematics---Moore flatly denies that it follows that he doesn't know that he has hands. Which, indeed, it doesn't.

Philosophers will disagree about the details here. But I think many, maybe even most, philosophers nowadays would agree with the main point I've been making: Simply showing that, in some sense, it is barely possible that p shows nothing as regards anyone's knowing that p.