Brian Hedden defends a radical view about the relationship between rationality, personal identity, and time. On the standard view, personal identity over time plays a central role in thinking about rationality. This is because, on the standard view, there are rational norms for how a person's attitudes and actions at one time should fit with her attitudes and actions at other times, norms that apply within a person but not across persons. But these norms are problematic. They make what you rationally ought to believe or do depend on facts about your past that aren't part of your current...