It’s not just semantics

Epistemology class was heavy going again tonight. We discussed semantic externalism as a refutation of scepticism. I don’t have a very good grasp of it yet, but it’s something along these lines:

1. Scepticism often uses the “brain in a vat” scenario (which these days could be called The Matrix scenario): how do we know that the world is as we think it is? Maybe we’re being fooled by an evil demon. Maybe we’re just a brain floating in a vat hooked up to a computer.
2. There is a philosophical view of language that says that the meanings of words are quite complex things, and not determined just by the words themselves. If a bug accidentally traces what looks like an image of Winston Churchill in the sand, there’s no “meaning” in its actions. If I have an image of a tree in my mind, but I don’t know what a tree is, I don’t know that it’s a tree I’m thinking of.
3. Semantic externalism says that if I’m a brain in a vat (or some other “sceptical state” where reality is removed from my experience of it) then I can’t really know that I am because I’ve got no real-world reference for it.
4. So, if I am brain in a vat then I can’t believe that I am. But I can imagine being a brain in a vat, so I therefore can’t be a brain in a vat.

Or something along those lines.

Technorati tags: philosophy – epistemology – skepticism – scepticism – semantic externalism