As time goes by, many things change. It is tempting to think that as things thus change, propositions reporting what is the case change in truth value. In a provocative paper, Kretzmann (1966) argued that being omniscient requires knowing different things at different times, and thus is incompatible with being immutable. This would constitute an objection to classical theism, according to which omniscience and immutability are both taken to be central attributes of God. Kretzmann’s argument was anticipated by Franz Brentano (1838–1917) in the following passage (not published until 1976):