I have had some harsh words for several of the materialists who deny infallible knowledge of self-evident truths such as A=A. Turns out I am in pretty good company.
An open mind, in questions that are not ultimate, is useful. But an open mind about the ultimate foundations either of Theoretical or of Practical Reason is idiocy. If a man’s mind is open on these things, let his mouth at least be shut.
C.S. Lewis, The Abolition of Man