Why Would God Make Physical Beings?

One objection to theistic arguments from design is that it seems as though God could have achieved most (if not all) of the goods of creating finite beings without bothering to make a physical world, complete with finely-tuned constants, life-permitting laws, and so on. As Neil Manson puts the objection:

The problem here for proponents of the fine-tuning argument is that, if God does exist, then clearly it is possible for there to be a non-physical intelligence. After all, God is supposed to be just such an intelligence. Why think God would prefer to create other intelligent, conscious beings by creating a life-permitting physical universe? God had other, seemingly much more efficient and sensible, options. For example, God could make Berkeley right. So even if they grant that God has a preference function over possible creations, fine-tuning sceptics are going to need to hear a lot more before they agree that that function favours the creation of a life-permitting physical universe – and favours it enough to make the fine-tuning argument persuasive. (2020, 315-316)

It seems that Thomists have available a potential response to this objection. Aquinas argues that only a material being can change its will over time: an immaterial entity (such as an angel) can only make one choice, fixing its will either for good or for ill. If this view of things is true, then we seem to have a good explanation for why God would want to make embodied beings: only they could experience repeated free moral choice, and all of the goods which come along with it (e.g. moral development, soul-building, deliberation, and so on).

Here are some other reasons why God might want to make physical beings. Firstly, the goods of sensory pleasure (including beautiful sights and sounds, gustatory pleasure, and so on) seem to require the existence of bodies. (Perhaps God could simply give disembodied minds the requisite pleasurable mental states without requiring any actual physical experiences. But there seems to be something off-putting about that; it smacks rather too much of a divine experience machine.) Secondly, one might argue that the unique aesthetic value of material beings would give God good reason to create them. (This is distinct from the just-discussed point about pleasure; beings can have objective aesthetic value even if nobody is around to derive sensory pleasure from the sight of them.) Thirdly, one could appeal to the point (made here) about God wanting to make a great variety of beings: it seems plausible that material beings can image the divine goodness in ways that no purely immaterial being could.

The Prior Probabilities of Theism and Naturalism

According to (what I think is) the right theory of intrinsic probability, there are three primary criteria which determine the prior of any given hypothesis:

1. Modesty: How little a hypothesis says about the world. 
• Example: "There is a living thing in my room" is a more modest claim than "there is a human being in my room," which in turn is more modest than "Richard Swinburne is in my room." More modest theories have more possible ways of being true: "There is a living thing in my room" could be true in any number of ways, "There is a human being in my room" in fewer ways, "Richard Swinburne is in my room" in only one way. Thus, more modest theories get a higher prior probability.
2. Coherence: How well the parts of a theory fit together, raising (or at least not lowering) one another's conditional probabilities.
• Example: "All Asian ravens are black and all non-Asian ravens are black" is a more coherent hypothesis than "All Asian ravens are black and all non-Asian ravens are white." (This is Draper's example.) Finding out that all Asian ravens are black increases the conditional probability that all of the non-Asian ravens are black, and vice versa. However, finding out that all Asian ravens are black reduces the conditional probability that all of the non-Asian ravens are white, and vice versa. So the parts of the first hypothesis raise one another's probability, while the parts of the second theory reduce one another's probability.
3. Brute limitations: Theories with arbitrary, inexplicable limitations should receive a lower prior than theories which lacks such limitations.
• Example: Consider two possible worlds, n and m. World n consists of a single particle moving at a constant finite velocity, while world m consists of a single particle moving at a constant infinite velocity. These two worlds seem to be equally modest and coherent: they both posit a single substance, behaving in a simple, uniform manner. Yet world m seems (to me at least) to be more intrinsically probable than world n. Why is this? The answer, I think, is that world n contains a brute limitation: why is the particle moving at the particular finite velocity that it is? Why not slightly faster, or slightly slower? World m, by contrast, has no such arbitrary limits. As such, it has a higher intrinsic probability.

(Note that this theory is largely a combination of Draper 2016 and Poston 2020.) It seems that if these three criteria are correct, then theism will always have an advantage over naturalism in terms of prior probability. The reason is this: the naturalist has to choose between coherence and a lack of brute limitations, whereas the theist can have both. Consider: if naturalism is true, then either every possible universe exists (i.e. there is something like a Lewisian multiverse), or else not. If not (i.e. if only one or some possible universes are realized), then the naturalist's theory will suffer from serious brute limitations. Why are these particular laws and physical structures instantiated, instead of all the other conceivable laws and physical structures which there could have been? Alternatively, if there is a Lewisian multiverse, then the naturalist's theory will avoid arbitrary limits, but only at the cost of an extreme lack of coherence (the Lewisian multiverse is just about the least uniform way that reality could conceivably be).

The upshot is that the naturalist faces an inevitable trade-off between coherence and a lack of brute limitations. The theist, however, faces no such difficulty: theism is both a highly coherent hypothesis (it posits a being with all possible perfections, which is a very uniform array of properties), and it is largely lacking in brute limitations (since God's properties are infinite). If all of this is correct, then it seems as though theism should get a relatively high prior as compared to naturalism.

Why Would God Make a Complex Universe?

While perusing Alexander Pruss' blog, I came across a post in which he offers this quote from Aquinas:

Hence we must say that the distinction and multitude of things come from the intention of the first agent, who is God. For He brought things into being in order that His goodness might be communicated to creatures, and be represented by them; and because His goodness could not be adequately represented by one creature alone, He produced many and diverse creatures, that what was wanting to one in the representation of the divine goodness might be supplied by another. For goodness, which in God is simple and uniform, in creatures is manifold and divided and hence the whole universe together participates the divine goodness more perfectly, and represents it better than any single creature whatever. (ST 1.47.1)

It occurs to me that this line of thinking could be used to support Swinburne's inductive cosmological argument, which goes like so: let "h" be theism, "e" be the existence of our universe, and "k" be our background knowledge (which in this case will consist only of logically-necessary truths). Since the physical universe is extremely complex, it is a priori very improbable that it should exist. However, Swinburne claims that God would have very good reason to produce such a universe, since he would be motivated to create embodied rational creatures, and such creatures would need a universe to live in. So P(e|h&k) is relatively high, while P(e|~h&k) is very low. Hence, P(h|e&k) > P(h|k).

Aquinas' aforementioned reasoning can, it seems to me, be used to substantially strengthen this argument. It does so by explaining why God would want to make a complex universe (such as we observe) rather than a very simple one, suited simply to the purpose of playing host to embodied rational agents. If all goodness involves participation in God (which it does), then (as Aquinas notes) the particular perfections of each individual type of creature can model the divine goodness in unique ways. This plausibly gives God good reason to make a varied and complex universe. This in turn raises P(e|h&k), thus strengthening the argument.