The next time someone dismisses you with the “Only science gives reliable truth” canard, ask if he wants you to take his statement as fact or simply as unsubstantiated opinion. If fact, ask what testable scientific evidence led him to his conclusion. As it turns out, this claim is not a fact of science. It is a philosophical assertion about science that itself cannot be proven by the scientific method and would therefore be unreliable, according to this approach.
– Koukl, Tactics