 Confronted with the existing problems for the Principle of Conditionalization, some Bayesians turn away from any diachronic norm and develop another variety of Bayesianism: time-slice Bayesianism. On this view, what credences you should (or may) have at any particular time depend solely on the total evidence you have at that same time—independently of your earlier credences. To specify this dependency relation is to specify exclusively synchronic norms—and to forget about diachronic norms. Strictly speaking, there is still a diachronic norm, but it is derived rather than fundamental: when the time flows from \(t\) to \(t'\), your credences ought to change in a certain way—they ought to change to the credences that you ought to have with respect to your total evidence at the latter time \(t'\)—and the earlier time \(t\) is to be ignored. Any diachronic norm, if correct, is at most an epiphenomenon that arises when correct synchronic norms are applied repeatedly across different times, according to time-slice Bayesianism. (This view is stated above in terms of one’s total evidence, but that can be replaced by one’s total reasons or information.)