theory of rationality that he calls Time-Slice Rationality (TSR). One of the main theses of TSR
is that all rational requirements are synchronic. We argue here first that this thesis is not well-
motivated. We also demonstrate that Hedden is in fact committed to an even stronger claim
about the rationality of an agent at a time. Finally, we provide some arguments against the
conception of rationality that results from this stronger claim.