 This norm allows the set of one’s certainties to expand or shrink, while incorporating the core idea of conditionalization: preservation of credence ratios. To see how this norm accommodates the Shangri-La Case, assume for simplicity that the traveler starts at the initial time with a set of certainties, which expands upon seeing the coin toss result at a later time, but shrinks back to the original set of certainties upon reaching Shangri-La at the final time. Note that there is no change in one’s certainties across the initial time and the final time. So, by the above norm, one’s credences at the final time (upon reaching Shangri-La) should be identical to those at the initial time (the start of the trip). In particular, one’s final credence in traveling the path by the Mountains should be the same as the initial credence, which is 0.5. For more on the attempts to save conditionalization from cases of actual or potential memory loss, see Meacham (2010), Moss (2012), and Titelbaum (2013a: ch. 6 and 7).