A Weaker Version of the Principle of Material Causality Yields the Same Conclusion

Recent versions of the cosmological argument deploy weaker causal and explanatory principles to make them more plausible: Perhaps the evidence isn't strong enough to support the claim that, necessarily (or at least, actually), every object or state of affairs (or some proper subclass thereof) has a sufficient reason or efficient cause of their existence or obtaining. And perhaps such principles beg the question against the atheist by assuming the causal or explanatory structure of a theistic universe. But surely (so the thought goes) the atheist's intuitive evidence supports the weaker claim that everything can have an efficient cause or sufficient reason. Such arguments go on from there to argue that a theistic conclusion can be gotten from such weaker principles.

In the same spirit, I think the principle of material causality can be weakened so as to be adequately supported by even the theist's intuitive evidence:

Weak PMC: Possibly, every concrete object (and aggregate of such) that has an originating or sustaining efficient cause has an originating or sustaining material cause, respectively. 

In simple terms, Weak PMC says that it is possible that all made things are made from or out of other  things. A bit more carefully, it says that there is at least one possible world in which all concrete individuals and stuffs that are made are made from or out of other concrete individuals or stuffs.

Now my own view is that a much stronger version of PMC is true -- viz., that it holds of metaphysical necessity. However, I'd be willing to bet that most people believe that PMC is non-vacuously true in at least the actual world, and for good reason: it's intuitive, it has no uncontroversial exceptions, and it's encoded in the well-confirmed conservation laws of physics. A fortiori, then, I think that even the theist has enough intuitive evidence to warrant the claim that there is at least one possible world W in which such a principle is non-vacuously true. But if so, then in W, there are concrete objects that are made, and all concrete objects that are made are made out of other things or stuff. And if so, then no concrete objects in W that are made are made ex nihilo, in which case no god or gods made them ex nihilo in W. But on classical Anselmian theism, for any world that contains concrete objects or stuffs distinct from God, at least some of those objects or stuffs were made ex nihilo.  It follows that the god of classical Anselmian theism doesn't exist in W. But if so, then by (i) the fact that classical Anselmian theism entails that God is a metaphysically necessary being, and (ii) Axiom S5 of S5 modal logic, it follows that such a God doesn't exist in the actual world, either.

Therefore, one can generate a successful argument from material causality against theism with even  a very weak version of PMC. How powerful of an argument is it?

Very powerful, I'd say. To see this, consider the following line of reasoning. Leaving aside formal and final causes, there appear to be four possible scenarios for causal principles that govern a universe:

(i) Both an efficient cause principle and a material cause principle

(ii) An efficient cause principle without a material cause principle

(iii) A material cause principle without an efficient cause principle

(iv) Neither an efficient cause principle nor a material cause principle

Here's the rub: our grounds for a material cause principle are at least as strong as our grounds for an efficient cause principle (I would say they're stronger for a material cause, as there appear to be counterexamples to the efficient cause principle in cases of certain quantum phenomena). But if so, then starting from the neutral standpoint of agnosticism, there is a default presumption in favor of (i) as one's epistemic starting point. Rejecting it in favor of one of the other three options therefore requires adequate grounds for doing so. But it's unproblematic for the atheist to start at (i).  By contrast, the theist has their work cut out for them: They must find grounds to reject (i) in favor of (ii).  But prima facie, it looks like no such grounds can be forthcoming.  For prima facie, any argument for theism will run afoul of Weak PMC, as Weak PMC blocks cosmological, ontological, and design arguments, and arguments from substance dualism as arguments for theism (as opposed to arguments for, at best, pantheism, panentheism, and demiurgism). It therefore looks as though the argument from material causality holds out the promise (or peril) of constituting an intrinsic defeater-defeater against classical Anselmian theism.

By contrast, it's not obvious to me that the same can be said of the standard arguments for atheism. For such arguments seem to be resistible if the theist can provide other grounds for theism, such as those mentioned above. But the problem is that, unlike the argument from material causality, the arguments from evil and hiddenness can't hamstring those arguments. It therefore seems to me that the argument from material causality holds out the prospect of being the most powerful argument against theism.

The argument from material causality also has other epistemic functions that are slightly weaker, yet still important. First, it can show that the theist incurs a theoretical cost by rejecting Weak PMC, as it seems to be supported by just about anyone's intuitive evidence (at least prior to reflecting on its implications and revising one's web of beliefs). Second, it can function as an undercutting defeater for the newer versions of cosmological arguments mentioned at the beginning of our discussion. 

In at least these ways, then, it seems to me that the argument from material causality is very powerful indeed.