Meant to reply earlier but thanks for the replies. Very helpful.

In Scholastic Metaphysics, one of the things Feser discusses is the simultaneity of essentially ordered causal series (pg 146):

Cause and effect are not two events, but two elements of one event. The basic idea is that to cause is just to produce an effect, and it makes no sense to think of a cause producing without its effect being produced, or an effect being produced without its cause producing it. As Clarke puts it, “the cutting-of-the-orange-by-the-knife must be identical with the-orange-being-cut; otherwise the knife is not cutting anything at the moment of its cutting, nor is the orange being cut by anything at the later moment of its being cut” (2001, p. 191).

Yet, when discussing arguments against PSR, Feser says the following (pg 141):

From a Scholastic point of view this sort of argument is a non-starter, since on the Scholastic understanding of PSR, propositions are not among the things requiring explanation in the first place, and explanation does not require logical entailment.

And (pg 142):

We have already noted that objections to PSR that assume that a sufficient reason for something must logically entail it misfire, since the defender of PSR need not make that assumption. Nor is the assumption plausible in any case.

If "it makes no sense" to think of the cause without its effect, then what is this but logical entailment? One of the criticisms Feser has made against Humean analyses of causation in other writings is that if cause and effect are thought to be simultaneous, it makes no sense to think of them as "loose and separate," and therefore no sense to think of, say, a brick pushing through glass without the glass shattering. Yet if this is the case, it seems the brick pushing through the glass entails that the glass breaks. Or, in other words, if cause / effect are two elements of the same event, how is it even possible not to have the effect if the cause is given?

If the relationshi

I think you might be misunderstanding Feser's argument. Thanks for the discussion though.

Sure. They're wanting to say their belief that PSR holds for some limited domain of reality occurs because such a view is supported by empirical evidence and the like.

But I don't see any reason to let them make the assumption if they're denying PSR. They might believe PSR only holds for some limited domain not because it is in accord with empirical evidence, but for no reason whatsoever.

The issue in the deniers' case is not with our faculties, specifically our rationality, but with reality. Reality within the universe conforms to our rationality (actually, for the materialistic evolutionist, it is the other way round), but that does not imply that the universe as a whole does too.

I know that, in their view, they’re not denying PSR ever holds. Rather, they are denying it everywhere and always holds. But this just raises the question: if PSR does not hold for all of reality, what reason could we have for thinking it holds for some subset of reality (more specifically, a subset that does not exclude our faculties)? Any reason would look suspiciously like PSR. But if they do not give a reason, then we’re back to the original problem.

Since the guy holding M1-M3 is a PSR denier, he doesn't really need a reason for holding them. He can just say "I feel better holding that than holding the PSR".

I’m not sure this is correct. Because it seems to me we would be justified in asking, “Yes, but do you believe that because you feel better holding it, or for no reason whatsoever?” And I don’t see how they can answer in the affirmative w.r.t. “because” if PSR is assumed false.

The position of limited PSR denial is not actually self-defeating, since it rejects PSR only as it applies to the ultimate explanation of the universe, not to explanations of facts within the universe. Sure enough that position is question-begging, as pointed out by Prof. Feser in this article

I’ve given reasons above for why I’m not sure I can agree that it isn’t self-defeating. On the other hand, I will say I like Della Rocca’s argument as well.