Abstract
In this paper, I argue (1) that the contents of some delusions are believed with sufficient confidence; (2) that a delusional subject could have a conscious belief in the content of his delusion (p), and concurrently judge a contradictory content (not-p) – his delusion could be transparent (Krstić 2020), and (3) that the existence of even one such case reveals a problem with pretty much all existing accounts of lying, since it suggests that one can lie by asserting what one consciously and confidently believes is true, and (4) sincerity, since it suggests that asserting a proposition you believe is true is neither sufficient nor necessary for sincerity. If I am right about (1) and (2), then (3) and (4) follow easily. Therefore, the paper is mainly devoted to an analysis of transparent delusion and defending (1) and (2).