In my view, the cosmological argument from contingency is the most powerful philosophical argument for the existence of God. By a ‘philosophical’ argument, in this context, I mean a way of giving reasons for something that does not depend on detailed empirical investigation, or on idiosyncratic features of a particular individual’s experience or psychology. Thus I do not hold that the argument from contingency is the best reason anyone has for believing in God. I think, for instance, that some people have had religious experiences which provide them with stronger reasons than the argument from contingency could, even making very generous assumptions about their ability to grasp the argument.
This belief of mine, about the relative strengths of the arguments, goes rather against the grain of current discussions. I think the recent philosophy of religion literature overestimates the power of the fine-tuning argument and the first cause argument, and underestimates the power of the argument from contingency.
(A couple of notes: first, I recognize that a great many philosophers have a very dim view of the first cause argument. Nevertheless many of them have a higher opinion of that argument than I do – or so it appears to me. Second, it is not perfectly clear that the fine-tuning argument satisfies my definition of a ‘philosophical’ argument above, since it depends on the discoveries of modern physics. However, it depends only on very general features of physical theory, and not on detailed examination of some particular class of phenomena, so I’m counting it as ‘philosophical.’)
Despite thinking the argument from contingency is a very powerful argument (as philosophical arguments go — I find myself in general agreement with Keith DeRose’s remarks about the limitations of philosophical arguments), I think there are three distinct credible responses to it, and that’s what I want to discuss here. The three credible responses are: (1) accepting the existence of a God-like necessary being; (2) rejecting the Principle of Sufficient Reason; or (3) holding some facts/entities discovered by physics to be necessary. The first two of these options have of course been much discussed, but the last one is less often addressed in work on the argument from contingency. Let me first lay out a version of the argument, and then discuss each of the responses.
A fairly standard version of the argument could go as follows:
- Every contingent fact has an explanation (PSR).
- It is a contingent fact that some contingent beings exist. Call this fact ‘(E)’.
- Therefore, (E) has an explanation (from PSR and 2).
- On pain of circularity, no contingent fact or contingent being could explain (E).
- If some contingent fact has an explanation, but is not explained by any contingent fact or contingent being, then it must be explained in terms of the free choice of a necessary being.
- Therefore, (E) must be explained in terms of the free choice of a necessary being (from 3-5).
- If some fact is explained in terms of the free choice of a necessary being, then there exists a necessary being who chooses freely.
- Therefore, there exists a necessary being who chooses freely, and this everyone calls ‘God’ (from 6 and 7).
Note first that this version does not require a ‘Big Conjunctive Contingent Fact,’ and hence need not get into any of the technicalities or weirdness of infinitary logic. Now let me quickly dismiss two responses I don’t regard as credible. The first response is the necessitarian denial of (2). I take it hardly anyone wants to take this route. The second is to deny (7) by holding that false propositions can be explanatory. This surprising thesis is ably defended by Nancy Cartwright, and perhaps there are some contexts in which Cartwright’s thesis is correct, but I take it to be quite clear that there is a metaphysical notion of explanation for which (7) holds. Cartwright (or a follower of Cartwright) might perhaps deny that every contingent fact has an explanation of this sort, while holding that every contingent fact has an explanation (or, more likely, many equally good explanations) of her sort. This response I do take to be credible, but, since the PSR, as I understand it, is about metaphysical explanations of the sort that validate (7), I’ll count this kind of response as a denial of the PSR.
Now, one way of responding to this argument is, of course, to accept it. As I have indicated, this is the response I favor, though I should note that I don’t want to commit too strongly to the technical adequacy of a hastily-drawn-up blog post version of the argument. There may be some technical difficulties, for instance, about (4). One might think that the fact that Kenny exists explains why some contingent beings exist in the sense that the former grounds or truth-makes the latter. This, though, is not the kind of explanation we’re going for. (There are many kinds of explanation.) The fundamental intuition is that ‘why is there something (contingent) rather than nothing (contingent)?’ is a perfectly well-formed question, and it makes sense to look for an answer to it, and the free choice of a necessary being is, uniquely, able to provide an answer to this question without rendering the contingent necessary. This seems (intuitively) quite right to me, and none of the critiques I’ve read have convinced me otherwise.
On the other hand, as I have said, there are two other possible responses which I take to be credible. The first of these is the rejection of the PSR. The leading reason given for rejecting the PSR is that it leads to necessitarianism. Those who take this response would hold that premise (5) of our argument is only vacuously true, since nothing necessary can explain anything contingent. There are some difficult issues here in the theory of explanation, but the view that, in correct explanations, the explanans must entail the explanandum is now widely regarded as false, so this general principle can’t be relied on here. But there is some kind of demand for explanation (something the proponent of the argument should be very sensitive to!): if the explanans is true in all worlds, then why is the explanandum false in some? Thus, for instance, if whatever accounts for the existence of contingent beings is also true at those worlds at which there are no continent beings, then why are there no contingent beings at those worlds? The appeal to free choice is supposed to answer this question, and if agent-causal libertarianism is coherent, then it’s pretty easy to see how the answer goes (see Pruss). But the coherence of agent-causal libertarianism is subject to much dispute, and it is unclear whether the problem is solved on alternative accounts of free choice.
This leads into the third response. Even if agent-causal libertarianism is incoherent, there is another kind of non-necessitating explanation which is now much more widely accepted: explanation in terms of indeterministic physical laws. This could provide an alternative method for getting from necessity to contingency, consistent with the PSR.
This kind of approach is suggested by last year’s debate between David Albert and Lawrence Krauss following Albert’s review of Krauss’s book. Albert insisted that Krauss had not explained why there was something rather than nothing because all Krauss had done was explain how, if we started from a state in which all of the quantum fields had the value zero everywhere, we would end up in a state where there is ‘something’ — that is, where the fields have the sorts of local spikes we call ‘particles.’ Albert’s objection was that explaining why the quantum fields are not everywhere zero is not explaining why there are quantum fields at all. Krauss’s response seems to be that the notion of ‘nothing’ with which Albert is working is wrong; that physics has discovered what nothing really is, just as chemistry has discovered what water really is, and, as it turned out, nothing is just all the fields being zero everywhere. It seems to me that a more or less equivalent (but more philosophically perspicuous) way of putting this claim would be to say that it is necessary that the quantum fields exist and obey the laws of physics, but contingent that there are any particles. Krauss can then show how, by indeterministic processes, particles are likely to arise from ‘nothing,’ i.e. from the absence of any particles. But note that this involves the existence of necessary beings: the quantum fields. It also involves making the laws of physics necessary; the laws of physics may or may not count as ‘beings.’
As I said, I take all three of these responses to be credible, by which I mean that the only way to decide between them are by the sorts of broad considerations that motivate theory choice. It seems to me that classical metaphysical theology – the sort of metaphysical system-building centered around a broadly Anselmian notion of God that we find, for instance, in Aquinas and Leibniz – exhibits, in a very high degree, the sorts of virtues we look for in metaphysical theories. It further seems to me that many of the people who take the physics approach do so out of some kind of general anti-metaphysical sentiment, which suggests that maybe the positivists were right: metaphysics, even analytic metaphysics, is a ‘gateway’ to theology. But – and this is my central point – this would have to be shown by a thorough comparison of the theoretical virtues of necessary being theology as compared with the necessity of physics.
(Cross-posted at blog.kennypearce.net.)