Response to Jeffery Lowder’s Case for Naturalism, Part 2

In the previous post, I examined Jeffery Jay Lowder’s bayesian case for naturalism over theism. There, my basic contention was that, as naturalism and theism are properly asymmetrical claims, they ought not be compared in a bayesian analysis. Instead, since the bayesian method ought to proceed cumulatively and progressively, we should start from similar, symetrical claims, such as naturalism and supernaturalism. Once we establish that supernaturalism is more probable than naturalism, we can then proceed to selecting between specific kinds of supernaturalism. In this way, I suggested, we can eventually arrive at theism as the most probable specific type of supernaturalism in general; and since supernaturalism is already more probable than naturalism, the most probable kind of supernaturalism itself will be established as more probable than naturalism. (Or, at least, the fact that supernaturalism is more probable than naturalism and that theism is the most probable kind of supernaturalism will significantly increase the prior probability of theism, overcoming its initial deficiency qua being a less modest claim than naturalism).

Lowder has responded that there are at least two lines of thought a naturalist could offer here: first, he could present a defeater to the claim that the universe is contingent. Second, he could present another argument in favor of naturalism over supernaturalism. Lowder hasn’t had an opportunity to flesh out the first option, so here we’ll focus on the second. Lowder suggests that, even if the contingency of the universe is evidence for supernaturalism over naturalism, there are other facts which still support naturalism over supernaturalism. The idea is that, when all the relevant evidence is weighed, naturalism still comes out on top.

In the previous post we already looked at one argument that might favor naturalism over supernaturalism (the very existence of a physical universe in the first place). But Lowder offers another as well: the continued existence of the universe favors naturalism. How so? He extrapolates in another article:

“So [theism] is not only compatible with God never creating the universe at all, but also with the possibility of God creating the universe and causing or allowing it to cease to exist.
In contrast, if N [naturalism] is true, then there exists no being or thing capable of knocking physical reality out of existence. (If a multiverse exists, maybe there is a physical process which can ‘knock’ baby universes out of existence just as there might be a physical process which can bring baby universes into existence. But there would be no physical process capable of knocking the multiverse as a whole out of existence.)
Since physical reality’s continuing existence is entailed by N but not by S[supernaturalism], this is additional evidence favoring N over T.” [1].

On supernaturalism, the universe could continue to exist from moment to moment, but certainly doesn’t have to; whereas, suggests Lowder, on naturalism, the universe must continue to exist from moment to moment. Hence, the fact that the universe does actually keep existing is evidence favoring naturalism over supernaturalism.

I think this is an interesting argument, and I’d like to take two approaches in responding. The first approach is to respond to the argument itself.

One preliminary question is whether or not the argument presupposes/depends upon a particular metaphysical theory of time. The argument seems to be committed to an A-theory of time, on which temporal becoming is a real feature of the world (the fact that if the universe exists at some T1, but could not exist at some later T2 in virtue of being “destroyed”, seems to imply that when T1 is actual, T2 is not yet actual). If it is the case that the argument depends upon this metaphysical commitment (which is rather controversial amongst scientists and philosophers), then that metaphysical position will need to be defended prior to the argument. Of course, many theists are already A-theorists anyways, and I myself do not yet have a set position on the subject, so I’ll set this question aside for now.

Next, I’d like to contend that naturalism itself does not in fact entail the continued existence of the universe. Recall Lowder’s definition of naturalism: naturalism is the hypothesis that “the physical exists and, if the mental exists, the physical explains why the mental exists” [2]. So, at least as defined here, naturalism entails that the physical universe exists, but not that it will continue to exist. Naturalism, as Lowder defines it, does not entail that the physical universe exists necessarily, nor that it will always keep existing. On naturalism, the universe could be necessary, but it could also simply be an inexplicable brute fact. If it’s the latter, then there’s no explanation for why the universe exists at the present moment, and no reason at all to think the universe will exist one second from now. Sure, there might not be anything outside the universe that could knock it out of existence, but there doesn’t have to be. The universe could simply stop existing, for no intelligible reason whatsoever. This is perfectly consistent with naturalism, and hence naturalism by itself does not predict that the universe will keep existing.

For this reason, I don’t think the argument works; the continued existence of the universe does not provide evidence for naturalism over supernaturalism. But let’s suppose for a moment that my objection is incorrect, and the argument does work. Or that some other argument or set of arguments in favor of naturalism over supernaturalism are proposed. There is still a second approach we can take in defending the claim that supernaturalism is more probable than naturalism. On this approach, we can simply grant that the various arguments in favor of naturalism work, but respond that the overall evidence still favors supernaturalism. Indeed, I’d contend that the argument for supernaturalism from the contingency of the physical universe, which I offered in the previous post, carries far more weight than both arguments for naturalism we’ve considered combined.

This claim, of course, requires defense. Notice that both pieces of evidence offered in favor of naturalism (existence of universe and continued existence of universe), while they might be more likely on naturalism, are still consistent with theism. I’d argue, however, that the contingency of the physical universe is completely inconsistent with naturalism. As such, the contingency argument is much stronger and weightier evidence for supernaturalism than the other arguments are for naturalism.

Why think that the contingency of the physical universe is actually inconsistent with naturalism? To fully and properly defend this would require a much more in depth treatment than I can give here; but a general case can be fleshed out. The argument will go something like this:

  1. For whatever exists, if its being is contingent, its being must be caused by something else
  2. The being of the physical universe is contingent
  3. Therefore, the being of the physical universe must have been caused by something other than the physical universe
  4. But, if naturalism is true, there cannot exist anything other than the physical universe which can act as a cause of the being of the physical universe
  5. Therefore, naturalism is false

Naturalism is inconsistent with the contingency of the universe because, if this argument is correct, the latter entails that the universe has an external cause, while naturalism entails that the universe does not have an external cause.

The argument here depends upon a version of what is commonly known as the “principle of succifient reason,” expressed in the first premise. However, it should be made clear that this version of the PSR is significantly different from the standard version discussed. The standard version of PSR defended since Leibniz has been a rationalist version; the version I’m using here, however, is a scholastic version. The latter can be formulated in a number of different ways. The great Domincan scholar Reginald Garrigou-Lagrange formulated it thus: “Everything that is has its raison d’etre, in itself, if of itself it exists, in something else, if of itself it does not exist” [3]. Contemporary philosopher Edward Feser, quoting Bernard Wueller, expresses it as: “there is a sufficient reason or adequate necessary objective explanation for the being of whatever is and for all attributes of any being” [4]. The premise I’ve used is simply a derivative of these: for whatever exists, if its being is contingent, its being must be caused [or explained] by something else.

Why think this principle is true? I follow St. Thomas Aquinas here in holding that this is a first principle of being and knowledge, analogous to the principle of identity or non-contradiction, albeit not quite as fundamental. “First principles,” as St. Thomas understands them, are principles which cannot properly be demonstrated, but which are required for and presuposed by any further reasoning whatsoever. For instance, without some form of the scholastic version of PSR, it seems we wouldn’t be able to trust our experiential knowledge. For my belief that “the tree that I see really exists” depends upon the assumption that my sense experience of the tree is actually connected to/explained by/caused by the real tree itself. If there were no causal connection between the tree and my experience of it, there would be no reason to think my experience is delivering accurate information [5].

Beyond this, however, a case can be made that even the sort of Bayesian arguments utilized by Lowder himself (and really any sort of rational argumentation whatsoever) depend upon the PSR in order to function. For Bayesian arguments just presuppose that pieces of data are intelligible and explainable phenomena; which wouldn’t be justified if PSR were false [6].

Finally, granted the first premise, why think the physical universe is actually contingent? Well, given the version of PSR we’re defending, a truly “necessary” being would have to be something which exists by and explains itself. Is the physical universe something like this? It doesn’t seem so. There are a variety of arguments which could be used in defense here. To summarize one very briefly: anything truly “necessary” must be absolutely, metaphysically simple, because anything “complex” or non-simple consists of parts, and there must be some cause/explanation for why those parts are connected as they are. (Don’t take this as a robust defense; this is meant merely as a sketch). But the physical universe clearly consists of parts, and hence cannot be a truly necessary being. Thus, it must be a contingent being, and must have a cause external to itself. If this is the case, then naturalism is necessarily false.

Notice that we do not even have to defend here that the “cause” of the universe is God, since we’re merely arguing for supernaturalism over naturalism. Once we’ve established this point, we can then go on to argue, as we did in the previous post, that theism specificially is the most probable kind of supernaturalism.




[3]. Rev. Reginald Garrigou-Lagrange O. P., Reality: A Synthesis of Thomistic Thought, Ex Fontibus, 2015. Page 29.

[4]. Edward Feser, Scholastic Metaphysics: A Contemporary Introduction, editiones scholasticae, 2014. Page 139-140.

[5]. Ibid., page 143. Feser drawing from work by Pruss and Koons here.

[6]. Ibid., 144. Again drawing from Pruss and Koons.

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