Foad Dizadji-Bahmani, 2013. The probability problem in Everettian quantum
mechanics persists. British Jour. Philosophy of Science   IN PRESS.

ABSTRACT. Everettian quantum mechanics (EQM) results in ‘multiple,
emergent, branching quasi-classical realities’ (Wallace [2012]). The
possible outcomes of measurement as per ‘orthodox’ quantum mechanics are,
in EQM, all instantiated. Given this metaphysics, Everettians face the
‘probability problem’—how to make sense of probabilities, and recover the
Born Rule. To solve the probability problem, Wallace, following Deutsch
([1999]), has derived a quantum representation theorem. I argue that
Wallace’s solution to the probability problem is unsuccessful, as follows.
First, I examine one of the axioms of rationality used to derive the
theorem, Branching Indifference (BI). I argue that Wallace is not
successful in showing that BI is rational. While I think it is correct to
put the burden of proof on Wallace to motivate BI as an axiom of
rationality, it does not follow from his failing to do so that BI is not
rational. Thus, second, I show that there is an alternative strategy for
setting one’s credences in the face of branching which is rational, and
which violates BI. This is Branch Counting (BC). Wallace is aware of BC,
and has proffered various arguments against it. However, third, I argue
that Wallace’s arguments against BC are unpersuasive. I conclude that the
probability problem in EQM persists.
Publications (a Ph.D. in Philosophy, London School of Economics, May 2012)
  ‘The Probability Problem in Everettian Quantum Mechanics Persists’,
British Journal for Philosophy of Science, forthcoming
  ‘The Aharanov Approach to Equilibrium’, Philosophy of Science, 2011
78(5): 976-988
  ‘Who is Afraid of Nagelian Reduction?’, Erkenntnis, 2010 73: 393-412,
(with R. Frigg and S. Hartmann)
  ‘Confirmation and Reduction: A Bayesian Account’, Synthese, 2011 179(2):
321-338, (with R. Frigg and S. Hartmann)

His paper may be an interesting read once it comes out. Also available in:
  ‘Why I am not an Everettian’, in D. Dieks and V. Karakostas (eds): Recent
Progress in Philosophy of Science: Perspectives and Foundational Problems,
2013, (The Third European Philosophy of Science Association Proceedings),
Dordrecht: Springer

I think this list needs another discussion of the possible MWI probability
problem although it has been covered here and elsewhere by members of this
list. Previous discussions have not been personally convincing.


You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
To post to this group, send email to
Visit this group at
For more options, visit

Reply via email to