…human brain is but a finite machine, therefore there are only finitely many propositions which you believe. Let us label these propositions p1, p2, …, pn, where n is the number of propositions you believe. So you believe each of these propositions p1, p2, …, pn. Yet, unless you are conceited, you know that you sometimes make mistakes, hence not everything you believe is true. Therefore, if you are not conceited, you know that at least one of the propositions p1, p2, …, pn is false. Yet you believe each of the propositions p1, p2, …, pn. This is straight inconsistency.

— Raymond M. Smullyan, What Is the Name of This Book?