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[Eckhart Aurelius Hughes]

Please use this topic to discuss Decoherence and Ontology by David Wallace, which is chapter 1 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 transcript at the end. Please do not post in this topic until you have read chapter 1.

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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 enjoyed reading this chapter. I think Wallace is a good writer based on read this. It was refreshing to have a more regular pace after the introduction which I felt had an unusual flow.

I felt he started and ended strong, but there were leaps in logic in between that didn't follow. Mainly, he seemed to want the many world interpretation (MWI) to not be considered an interpretation of quantum mechanics but to be considered part of the theory itself. However, his arguments for his seem admittedly very philosophical, and of course contentious, which seems to contradict the status of not being an interpretation of the science but being the science itself. The question and answer that is missing, in my analysis, is exactly what it means for something to be an interpretation of a scientific theory/fact as opposed to being a scientific theory/fact, which could lead to several different types of interpretations varying in degree of removal from the theory itself. At one point, Wallace uses a useful analogy of dinosaurs, confidently claiming in other words that MWI is as scientifically supported as the fact the dinosaurs existed at all. But that may not be a fair comparison, and I don't think in my inexpert, laymen analysis of his expert writing that he has shown that it is. Rather, I suspect it might be the case that MWI is closer to the specific dinosaurs, with specific guessed traits, supposed on a Discovery Channel animation of a dinosaur which goes well beyond the bare theory of dinosaurs existence, which entails conjecture about what colors dinosaurs were, whether they had feathers, how they behaved and so forth. These things are interpretations of dinosaurs, and they may be consistent with the evidence, they may even be somewhat reasonable abductions or best guesses based on the evidence, far different and more reliable than baseless conjecture or baseless wild speculation, but we can certainly see that at some point between the scientific theory of dinosaurs from the evidence and the most wild, baseless speculation (e.g. perhaps, that the magical, supernatural devil planted the fossils to trick us) lay a point in which one is interpreting the evidence to answer questions that the evidence doesn't directly answer as a mere uninterpreted scientific theory. I suspect a more detailed investigation of what it means for something to be an interpretation of scientific theory and empirical facts (e.g. the animation of the dinosaur with detail beyond what is strictly entailed by the scientific theory sans interpretation) as opposed to being the theory and facts themselves (e.g. the incomplete facts we know about dinosaurs that are not enough to form a full animation for the Discovery Channel without some extra 'best guessing' albeit evidence-inspired and evidence-consistent).

Moving on, I think Wallace does a good job differentiating MWI with sci-fi versions of parallel universes, and similarly pointing out how some of the arguments used against MWI are thus really strawman arguments. Also, I think Wallace did a great job explaining the concept of emergence.

One somewhat incidental line that I found particularly interesting even out of the context of MWI is the following which I feel raises questions about Wallace's views on consciousness and personal identity:

What makes it true that (say) a given lump of organic matter has intentions and desires is not something derivable algorithmically from the lump's microscopic constituents; it is the fact that, when it occurs to us to try interpreting its behavior in terms of beliefs and desires, that strategy turns out to be highly effective.

The idea that consciousness and personal identity and the things that go along with that like beliefs and desires is emergent is not new and is -- I think -- agreeable, particularly among the non-religious. But this line seems to suggest that it is not only emergent but imaginary, like when we personify a natural event to explain it -- i.e. create a simpler, but useful predictive model -- to a child (e.g. "the storm got tired and decided to rest").

Finally, I wanted some input about the following paragraph, which addresses the potential "sceptic" who argues that the quantum state is running a simulation of the classical world, and which I found especially interesting from the perspective of discussing the book on a philosophy forum but yet unclear:

Note firstly that the very assumption that a certain entity which is structurally like our world is not our world is manifestly question-begging. How do we know that space is three-dimensional? We look around us. How do we know that we are seeing something fundamental rather than emergent? we don't; all of our observations [...] are structural observations, and only the sort of a prioristic knowledge now fundamentally discredited in philosophy could tell us more.

I mostly agree with the points of the argument by Wallace of which that paragraph is a a part, but I am especially concerned with what is meant by that last sentence. Is Wallace claiming that the existence of a priori knowledge is fundamentally discredited in philosophy? If so, I do not feel that this claim, regardless of whether I personally agree with it, has any kind of near unanimous agreement in philosophy, and as such I do not see how it has a place essentially as a premise in Wallace's argument. Alternatively, I could be misreading him and he does not mean to say all a priori knowledge is discredited, but means to refer to a specific subset of a priori knowledge which happens to specifically be discredited in contrast to other types of a priori knowledge, but then I do not know what this subset is exactly. Either way, I fear Wallace has glossed over a philosophical point that cannot reasonably be glossed over like that. What do you all make of this?

Anyway, please post any other comments or questions you have about this chapter!