It’s not the thought that counts

Let’s say that the mentalist about evidence believes the following supervenience thesis:

M: Necessarily, if A and B are in the same non-factive mental states from the cradle to the grave, A and B will share the same evidence from the cradle to the grave.

Here’s an argument against mentalism, so understood:

(1) We have non-inferential knowledge of the external world.
(2) If we know p non-inferentially, p is part of our evidence.
(3) If ~p, p is not part of our evidence.
(4) It is possible for someone to be in just the same non-factive mental states as any one of us and believe mistakenly that p.
(5) We know p non-inferentially.
(C) It is possible for someone to be in just the same non-factive mental states as any one of us and while p will not be part of their evidence, p will be part of ours.

Continue reading