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Theism, Substance Dualism, Personal Identity, and Quantum Mechanics

(Extremely rough draft.)

Ever since at least Ladyman and Ross's Every Thing Must Go (with David Wallace, Peter Lewis, David Albert, Tim Maudlin and many others in chorus) more and more philosophers have been coming to grips with the need for radical revisions in traditional analytic metaphysics in the light of  quantum mechanics (QM) (cf. Jenann Ismael, Alyssa Ney, Peter Lewis, Kerry McKenzie, Jessica Wilson, Jonathan Schaffer, Ted Sider, Shamik Dasgupta, and many others).[1]   However (aside from worries for the causal principle in cosmological arguments), it seems that the waves of the quantum revolution have yet to be felt in contemporary analytic philosophy of religion. I noted one potential implication on another occasion. Here are a few more.

Prima facie, on any plausible interpretation of quantum mechanics (Bohmian, Everettian, and GRW), there are many worlds/universes. As Peter Lewis points out, non-Everrettian interpretations of quantum mechanics are just many-worlds accounts in denial[2]. This has serious implications for the metaphysics of personal identity and other issues related to philosophy of religion. 

For example, take standard theistic accounts of substance dualism, and take the increasingly popular Everettian interpretation of QM (in fact, strictly speaking, it's not an interpretation: it just is QM). On that account, humans are constantly branching, hydra-like, into hugely many alternate universes, at virtually every moment of their lives. But if so, then prima facie, either (i) only one branch is you, or (ii) they all are you. On (i), God creates (directly, ex nihilo, or indirectly, through natural processes) new souls for each branch self at virtually every moment. On (ii), you have many selves. On either option, the sameness of soul account of personal identity is starting to look seriously unmotivated.

Furthermore, what are we to make of the afterlife? On (ii), all of your counterpart branch souls have an existence in an afterlife. Now combine that with the traditional doctrine of the soul being joined to a physical body at the final judgement.  Prima facie, our world essentially involves QM and branching universes, in which case ,prima facie, so does any post-resurrection universe. Prima facie,   all of the branching selves will be resurrected in different alternate universes, with counterpart Christs. On (i), it's hard to get an intelligible grasp of how all of my branching selves could be "me", each in their own resurrected bodies in alternate universes.

Furthermore, what are we to make of the person and work of Christ? For example, Jesus has many branch selves. Which one is the "real" Jesus? One? Some? All? Presumably, then, there are many Christs, and there will have to be many crucifixions. From this example, it becomes apparent that a host of other problems arise for the incarnation, atonement, trinity, and related doctrines. 

In short, it looks as though quantum mechanics poses serious problems for both substance dualism and for theism. In fact, it's looking as though QM, all by itself, is incompatible with-- or, at the very least, highly surprising on -- traditional accounts of Christian theism and religious monotheism in general. Prima facie, then, QM provides at least strong abductive evidence against traditional monotheism.

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[1] The other main revolution in physics is relativistic quantum field theory (RQFT), according to which fields are more fundamental than particles: what we call 'particles' are really just field excitations. But that is another can of worms.
[2] Lewis, Peter J. Quantum Ontology: A Guide to the Metaphysics of Quantum Mechanics (Oxford: Oxford University Press, 2016).


Review of Trakakis' (ed.) <i>The Problem of Evil: Eight Views in Dialogue</i>

Daniel Johnson reviews the book for NDPR .