Thoughts on the Principle of Material Causality

Felipe Leon's Argument Against Creation Ex Nihilo

Felipe Leon has recently put forth an argument against traditional theism, based on what he calls the "Principle of Material Causality" (PMC). In essence, this principle states that "All concrete objects that have an originating or sustaining efficient cause have an originating or sustaining material cause, respectively." This principle, Leon notes, is incompatible with traditional theism, as it entails that God could not have created the universe "ex nihilo" (i.e. without a pre-existing material cause).

What is more, Leon argues that PMC is supported by all of the same considerations typically marshalled in support of theism-friendly causal principles (such as the Kalam causal principle). As such, theists who accept those principles ought, on pain of inconsistency, to accept PMC as well. But since PMC entails the falsity of creatio ex nihilo (and therefore, of traditional theism), it follows that theists ought to give up their belief in God. How successful is this argument? Let's take a closer look.

Potential Responses to Leon's Argument

There are, by my lights, at least two potential replies that the theist might offer to Leon's argument. Firstly, it is not entirely clear that PMC has empirical support. Secondly, there are a number of potential symmetry breakers that distinguish, say, the Kalam principle from PMC. Let's examine each of these options in order, beginning with potential empirical counterexamples.

Objection #1: Empirical Counterexamples

Leon states that his PMC "rules out concrete objects that have an originating or sustaining efficient cause, but lack a material cause." Hence, if any examples of such objects can be found, PMC would thereby be falsified.

Do we know of any such objects? Well (my thanks to Alex Pruss for this example), it seems that virtual particles are a plausible candidate: they have an originating efficient cause (i.e. the fundamental physical entities, governed by the laws of nature), but they arguably do not have a material cause. This is because the vacuum fields from which the particles emerge are not diminished in any way, which is plausibly required in cases of material causation.

Why should we think that a reduction of source is required for material causation? Think of Aristotle's example of the statue: we begin with a lump of bronze, which we then draw from in order to make the statue. Supposing that we began with 100kg of bronze, we would not still have 100kg left after making the statue. If we did—that is, if the pile of bronze were completely undiminished—then in what sense can we say that the statue is "made from" the bronze? Remember, it is not enough for the statue to be made of just any bronze; it must be made of that bronze, in order for that bronze to count as its "material cause."

Now, apply this principle to the case of virtual particles: if the vacuum fields from which they emerge are entirely undiminished, then it what sense could we possibly call those fields the "material cause" of the particles? This seems like a plausible counterexample to PMC. At the very least, such a case must count against Leon's claim that PMC enjoys empirical support on par with, say, the Kalam principle.

Objection #2: Symmetry-Breakers

Leon argues that PMC "looks to be on an epistemic par" with a more general theism-friendly principle, which he calls IUC. This principle states that it is "metaphysically impossible for a concrete object to come into existence out of nothing without a cause." However, I think there are a number of important differences between these two principles.

For one thing, IUC arguably follows from a powers theory of modality, in a way that PMC does not. The bare claim to which a powers theorist must be committed is that causal powers set the bounds of modal space. This plausibly means that IUC is a basic commitment of powers-based modal theories, whereas PMC is an additional, optional commitment; after all, many powers theorists (such as Alex Pruss) reject PMC, whereas it is not clear how a powers theorist could reject IUC.

For another thing, there might be an epistemological symmetry breaker here as well. For denying IUC seems like it may well threaten global skepticism, as the concrete constituents of our sense experience (e.g. photons, sound waves, etc.) may have simply emerged uncaused. PMC, on the other hand, does not seem to threaten our knowledge in the same way. Suppose arguendo that our above-discussed example of virtual particles really did serve to falsify PMC. Would we feel that our knowledge of the external world had been somehow impugned? I think not. By contrast, the falsity of IUC would plausibly threaten our knowledge (see Pruss and Koons' paper on skepticism and the PSR).

Conclusion

With all of that said, it seems clear to me that theists have a number of plausible options for denying Leon's PMC. There are also two additional options that I have not considered here: for one thing, it is arguably possible for traditional theism to accommodate PMC; for example, see this paper on Aquinas' doctrine of creation. For another thing, it seems that a theist could simply accept the additional theoretical cost that comes along with denying PMC, even without additional argumentation. Of course, this last route is costly, and therefore, the theist should, it seems to me, prefer the earlier options.