Philosophy Discussion Forums | A Humans-Only Club for Open-Minded Discussion & Debate

[Eckhart Aurelius Hughes]

Please use this topic to discuss How to Prove the Born Rule by David Wallace, which is chapter 8 of the July book of the month Many Worlds?: Everett, Quantum Theory, & Reality edited by Saunders, Barrett, Kent, Wallace. We are discussing this book chapter-by-chapter, including a discussion for the introduction and the two transcripts. Click here for the organized linked list of each chapter's discussion. Please do not post in this topic until you have read chapter 8.

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What do you think of this chapter? What do you think of Wallace's ideas and arguments? If you chose mostly disagree or utterly disagree for the poll, then on what specifically do you disagree with Wallace?

I think Wallace makes many excellent and intelligent points. This isn't the first chapter he wrote. Sometimes his writing is very technical, but I think he organizes his papers well and does a great job critically analysis his own arguments and addressing potential misunderstandings or attempted points of rebuttal. However, I think maybe his overall argument in this chapter about probability is moot in a lot of ways. His argument presupposes that MWI is correct, but isn't that to sidestep the whole problem that MWI allegedly has with probability (as argued in the opening of the following chapter) in that it is through the accuracy of probabilities that quantum mechanics is validated at all to even open the door to MWI? Moreover, I wonder whether or not one really needs to deal with probability to try to come up with something besides everyday epistemic probabilities based on our ignorance and assuming that assumed symmetries lead to equal chances (e.g. that a 6-sided die has 1/6th chance landing on any side). Indeed, Wallace seems to support the Born Rule through a process of elimination and an assumption that we need some rule to support probability particularly for rational agents, but I doubt we need such a rule. That is, essentially, I think that we can say real, ontological probability does not exist in a deterministic reality and that all probability is simply that same old epistemic probability.

I enjoy the way Wallace writes in dialogue form during a portion of the chapter.

One relatively incidental point about the significance of ordering being supported by more then mere intuition really resonated with me philosophically:

Excluding stylized and occasional exceptions, then, ordering is constitutive of rationality, not just intuitively necessary for it.

I have stressed this because, in fact, very much the same defense can be offered of the less-familiar diachronic consistency principle, which in effect rules out the possibility of a conflict of interest between an agent and his future selves. In philosophy, examples one often speaks of a (classical) agent as if he were a continuum of independent entities, one for each time, each having his own preference ordering. But of course actual decision-making takes place over time. An agent's actions take time to carry out, his desires and goals take time to be realized. If his preferences do not remain consistent over this timescale, deliberative actions is not possible at all.

This brings up some philosophical issues that are hard to resolve but casts an interesting light on them by showing how a common philosophical model is clearly wrong -- that model being the idea of an agent as simply a collection of momentary or 3-D persons each with its own potentially different set of desires. It still leaves open the problem that people are not rational agents and often do not adhere to a principle of diachronic consistency, such as in Wallace's wine example. I think the fact that any discussion about this Everettian probability requires assuming something clearly false shows that it is a classical-style approximation that really has no need to be considered to exist at all.

Anyway, what do you all think?