Solution(?) to the Everettian Evidential Problem

          @misc{ pirsa_PIRSA:07090066,
            doi = {10.48660/07090066},
            url = {https://pirsa.org/07090066},
            author = {Greaves, Hilary},
            keywords = {},
            language = {en},
            title = {Solution(?) to the Everettian Evidential Problem},
            publisher = {Perimeter Institute},
            year = {2007},
            month = {sep},
            note = {PIRSA:07090066 see, \url{https://pirsa.org}}
          }
          

Abstract

This talk follows on from Wayne Myrvold\'s (and is based on joint work with Myrvold). I aim (and claim) to provide a unified account of theory confirmation that can deal with the (actual) situation in which we are uncertain whether the true theory is a probabilistic one or a branching-universe one, that does not presuppose the correctness of any particular physical theory, and that illuminates the connection between the decision-theoretic and the confirmation-theoretic roles of probabilities and their Everettian analogs. (The technique is to piggy-back on the existing body of physics-independent decision theory due to Savage, De Finetti and others, and to exploit the pervasive structural analogy between probabilistic theories and branching-universe theories in arguing for a particular application of that same mathematics to the branching case.) One corollary of this account is that ordinary empirical evidence (such as observed outcomes of relative-frequency trials) confirms Everettian QM in precisely the same way that it confirms a probabilistic QM; I claim that this result solves the Evidential Problem discussed by Myrvold. I will also briefly discuss the relationship between this approach and the Everettian \'derivation of the Born rule\' due to Deutsch and Wallace.