Many requirements of rationality rely for their application on facts about identity at a time. Take the requirement not to have contradictory beliefs. It is irrational if a single agent believes P and believes ¬P, but it is not irrational if one agent believes P and another believes ¬P. There are puzzle cases, however, in which it is unclear whether we have a single agent, or instead two or more. I consider and reject possible criteria of identity at a time before proposing a deflationary, pragmatist alternative. On this view, there are no deep facts about whether we really have a single agent or multiple agents. Instead, whether we should treat an entity as constituting a single agent or multiple agents depends on our own purposes in using rationally evaluative language. This pragmatist view allows for group agency, and in this way consideration of puzzle cases for identity at a time provides new motivation for the possibility of group agents. This response to puzzle cases for identity at a time also undermines one motivation for adopting a purely synchronic theory of rationality in response to analogous puzzle cases for identity over time.