 The issue, named by Wallace 2003 as the “incoherence” probability problem, is arguably the most serious difficulty. How can one talk about probability when all possible outcomes happen? This led Saunders and Wallace 2008a to introduce uncertainty to the MWI, see recent analysis in Saunders forthcoming-b. However, Section 4.2 shows how one can explain the illusion of probability of an observer in a world, while the Universe incorporating all the worlds remains deterministic, see also Vaidman 2014. Albert 2010, 2015 argue that Vaidman’s probability appears too late. Vaidman 2012 and McQueen and Vaidman 2019 answer Albert by viewing the probability as the value of a rational bet on a particular result. The results of the betting of the experimenter are relevant for his successors emerging in different worlds after performing the experiment. Since the experimenter is related to all of his successors and they all have identical rational strategies for betting, then this should also be the strategy of the experimenter before the experiment.