Reply To: Retrocausality is intrinsic to quantum mechanics

Daniel Rohrlich

Dear Travis and Aurelien, this time it seems most appropriate to address you together.

I agree that we have no proof that quantum mechanics is retrocausal, or for that matter that quantum mechanics is not retrocausal. Some interpretations via their definition leave no room for retrocausality, but then they don’t show that retrocausal thinking could not be helpful. That said, let me return briefly to the motivation for my claim in “A reasonable thing that just might work”. Aurelien, you are right! My interest in formulating quantum mechanics as a locally causal-retrocausal theory is that it might lead us to a quantum ontology that we can live with, free of “spooky action at a distance”. In trying to persuade others, but mostly myself, that quantum mechanics could be a locally causal-retrocausal theory, I came to the Alice-Bob-Jim thought experiment at the top of this page, and found it charming. To me, at least, it is just apt and natural to think of Jim’s choice as part of the preparation of the ensemble that Alice and Bob measure. After all, if variables A and B are correlated – as Jim’s choice is correlated with the kind of the correlations that Alice and Bob measure – and A is a human choice – isn’t it then that we say A caused B? And there is no paradox of causal circularity or free will.

Again, with many thanks to all,

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