Assertion, Evidence, and the Future

This essay uses a puzzle about assertion and time to explore the pragmatics, semantics, and epistemology of future discourse. The puzzle concerns cases in which a subject is in a position to say, at an initial time t, that it will be that ϕ, but is not in a position to say, at a later time $t′$⁠, that it is or was that ϕ, despite not losing or gaining any relevant evidence between t and $t′$⁠. We consider a number of approaches to the puzzle and defend the view that subjects in these cases lose knowledge simply by moving through time.