it was not long before I came to this:
A ‘brain in a vat’ (BIV) is fed apparently normal perceptual experiences, just like you and I are having, by a computer simulation run by an evil scientist. Orthodoxy addresses the following skeptical argument:
For any person, S:
- If S is not in a position to know that she is not a BIV, then she cannot know that she has hands.
- S is not in a position to know that she is not a BIV.
- S cannot know that she has hands. (inferred from 1 and 2)
If you can’t even know that you have hands, then you can’t have any empirical knowledge at all.
The philosophical problem is that the argument is logically valid, the premises all seem true, but the conclusion seems false….
NO! The premises don’t “seem” true.. because they obviously aren’t even close to being “true”. In fact #1 is obviously false! A BIV is just as sure that she has hands as I am …. because she DOES! Her hands are to her just like mine are to me, ie aspects of her experience which she feels the ability to use for grasping and controlling other aspects of her experience. This is not a problem unless one interprets “knowing” that one “has hands” as something none of us can ever be sure of.