A formal proof of the Born rule from decision-theoretic assumptions

Abstract

I develop the decision-theoretic approach to quantum probability, originally proposed by David Deutsch, into a mathematically rigorous proof of the Born rule in (Everett-interpreted) quantum mechanics. I sketch the argument informally, then prove it formally, and lastly consider a number of proposed ``counter-examples'' to show exactly which premises of the argument they violate.Comment: 36 pages. To appear (under the title "How to prove the Born rule") in Saunders, Barrett, Kent and Wallace, "Many Worlds? Everett, Quantum Theory, and Reality" (Oxford University Press