 In an ambitious work Deutsch 1999 claimed to derive the Probability Postulate from the quantum formalism and classical decision theory. In Deutsch’s argument the notion of probability is operationalised by being reduced to an agent’s betting preferences. So an agent who is indifferent between receiving $20 on those branches where spin “up” is observed and receiving $10 on all branches by definition is deemed to give probability 1/2 to the spin-up branches. Deutsch then attempts, using some symmetry arguments, to prove that the only rationally coherent strategy for an agent is to assign these operationalised “probabilities” to equal the quantum-mechanical branch weights. Wallace 2003, 2007, 2010b, 2012 developed this approach by making explicit the tacit assumptions in Deutsch’s argument. In the most recent version of these proofs, the central assumptions are (i) the symmetry structure of unitary quantum mechanics; (ii) that an agent’s preferences are consistent across time; (iii) that an agent is indifferent to the fine-grained branching structure of the world per se. Early criticisms of the Deutsch-Wallace approach focussed on circularity concerns (Barnum et al. 2000, Baker 2007, Hemmo and Pitowsky 2007). As the program led to more explicit proofs, criticism turned to the decision-theoretic assumptions being made Lewis 2010, Albert 2010, Kent 2010, Price 2010). The analysis of the Deutsch-Wallace program continues in a flurry of (mostly critical) papers Adlam 2014, Dawid and Thébault 2014, Dawid and Thébault 2015, Dizadji-Bahmani 2015, Jansson 2016, Read 2018, Mandolesi 2018, Mandolesi 2019, Araujo 2019, Brown and Ben Porath 2020, Saunders forthcoming-b.