December 9, 2013

Oppy on Theism, Naturalism, and Explanation

In his contribution to Goldschmidt's The Puzzle of Existence, Graham Oppy argues that, "as [a] hypothes[i]s about the contents of global causal reality" (p. 51), naturalism is ceteris paribus preferable to theism. Oppy's strategy for defending this claim is to consider three hypotheses about the structure of global causal reality, and argue that naturalism is superior to theism on each hypothesis. Here are his three hypotheses:

  1. Regress: Causal reality does not have an initial maximal part. That is, it is not the case that there is a part of causal reality which has no parts that stand in causal relations to one another and (b) is not preceded by some other part of causal reality which has no parts that stand in causal relations to one another.

  2. Necessary Initial Part: Causal reality has an initial maximal part, and it is not possible that causal reality had any other initial maximal part. On the assumption that the initial maximal part involves objects, both the existence and the initial properties of those objects are necessary.

  3. Contingent Initial Part: Causal reality has an initial maximal part, but it is possible that causal reality had some other initial maximal part. On the assumption that the initial maximal part involves objects, at least one of the existence and the initial maximal properties of those objects is contingent (p. 49).

According to Oppy, given Regress theism has no explanatory advantage over naturalism, since both appeal to infinite regress, but naturalism is more parsimonious than theism, hence it is preferable.

The idea that causal reality has an initial part, whether necessary or contingent, might be thought most favorable to theism, but Oppy thinks the case here is really no different than Regress. The reason for this is simple: he doesn't see why an initial supernatural state is any better, from an explanatory perspective, than an initial natural state (regardless of whether we take the initial state to be necessary or contingent). So, from an explanatory perspective, the hypotheses are again equal, but from a simplicity perspective naturalism wins again.

In my last post, I promised to return to O'Connor's discussion of the 'all things considered' preferability of theism to naturalism. O'Connor concedes Oppy's claim (in previous work) that naturalism is preferable in terms of parsimony, but insists that "Naturalism simply is not a rival explanatory scheme for existence to Theism" (p. 39). In other words, naturalism, according to O'Connor, does not even try to explain what theism tries to explain. What Oppy gives in his article here is an "anything theism can do naturalism can do better" retort. If the theist posits a necessarily existing supernatural being, naturalism can posit a necessarily existing natural state/being. If the theist posits a contingently existing supernatural being, the naturalist can posit a contingently existing natural being.

Now, as Oppy concedes (p. 51), there is some difficulty about this natural/supernatural distinction. But what Oppy essentially has in mind, is that we are better of positing 'more of the same' than positing something totally different (like a God).

Oppy's key point is that positing God as one more 'billiard ball' in the sequence of causes studied by science yields no explanatory advantage. Surely he is right about this. As long as God is considered as one more billiard ball, we are better off with a natural billiard ball than a supernatural one. In my view, insofar as O'Connor is considering God as a cause among causes (and he seems to be), Oppy's critique is devastating.

However, the point that there is no explanatory advantage to positing God as one more billiard ball was already recognized by classical theistic metaphysians such as Aquinas and Leibniz. This is, after all, precisely the point of the traditional distinction between primary and secondary causation: God is not a cause among causes, but rather stands outside the secondary causal sequence and makes that sequence, rather than another, actual. As has long been recognized, this is consistent with the sequence of secondary causes being either finite or infinite, for even if there was an infinite sequence, we could ask, 'why that sequence and not another?' and we could still answer, 'because God so chose.'

Oppy will quite rightly respond that it is incumbent on the theist to render this notion of 'primary causation' intelligible. However, recent work in analytic metaphysics on 'grounding' and 'building relations' (as Karen Bennett calls them) suggests that this can be done. In brief, it is now (again) recognized that there are a plurality of metaphysical relations that can ground explanation. The theist wants to say that this causal sequence exists because God chose it. This 'because' need not signify the same causal relation by which (literal or metaphorical) billiard balls are regularly related to one another. Just exactly what the theist should take primary causation to be, and exactly how it should be seen as relating to other grounding or building relations, is an interesting topic for further research. But the long and short of it is, even if not much can be said about exactly what primary causation is, if primary causation is a species of building relation, and we understand building relations in general, and we are independently committed to a plurality of them, then it seems to me that the ideological cost of believing in primary causation is not so great as to offset the benefit of explaining something the naturalist doesn't even try to explain: namely, why this causal sequence is actual.

Now, that theism can overcome this ideological cost is not enough to show that it is preferable, for this is not the only cost of theism. God is supposed to be a really (fundamentally) existing entity, and hence positing a God is itself an ontological cost. If God is a sui generis entity in a fairly strong sense (as opposed to, for instance, to literally being a mind), then there is also a significant ideological cost here. One alternative is to posit some necessary laws of nature (or something like that) to make the causal sequence go the way it does, but if one uses the word 'God' in such a way that 'impersonal God' is not a contradiction in terms, then this sounds like an impersonal God. Let's set that aside. There's a more basic issue to concern us. One way or another, we're paying a lot to get an explanation of why this causal sequence is actual. If, as Shieva Kleinschmidt argues in the very next chapter, the Principle of Sufficient Reason is false and explanatory comprehensiveness is merely one theoretical virtue among many, then perhaps the cost is greater than we should be willing to bear. More on this next time.

(Cross-posted at The Prosblogion.)

Posted by Kenny at December 9, 2013 6:38 PM
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