But I think that doesn't quite get things in the right order. Huemer, if he is correct, we can trust our cognitive faculties. But that seems to be apart from any other theoretical commitments we had. I would argue that if say we can generally trust our cognitive faculties, then we can't commit to a position that implies we have no reason for generally trusting our faculties, whether this be a naturalistic account of the mind or denying the PSR. If we have no reason to think our cognitive faculties are generally reliable, it seems hard to see why we could generally trust them. But we can generally trust them. If Huemer's position is that we can subscribe to positions that deny any reason for thinking their is general reliability to our cognitive faculties, and yet still trust them, then he is wrong. But I'm not sure he is doing this. This seems a leap from what you describe.

If we accept Huemer's position. If he is suggesting we can generally accept the reliability of our cognitive faculties, whilst accepting positions that give us no reason to generally accept our cognitive faculties, I think he is wrong.

I'm not sure his position is strictly relevant though, as he doesn't seem interested in the same debate. He is talking about how we know we can trust our cognitive faculties, which Feser (and Reppert)/already accept. They are discussing other beliefs that may clash with such acceptance.

Well, I would say that all philosophy except for inquiries into the foundation of knowledge presuppose the reliability of our faculties. That is why sceptical worries are only brought up in narrow epistemological areas of philosophy, except in the way Feser or Reppert bring them up. I think Feser (and Reppert) assume we do have reliable faculties, and are justified in doing so, given the kind of arguments they are. Arguments for that assumption are not germaine to their level of argument. After all, these aren't the kind of arguments over which one actually comes to be or not be a sceptic.

RomanJoe, I think your question to Jeremy gets at one of the reasons I brought up Huemer's epistemology, called phenomenal conservatism, elsewhere in this topic. Without reiterating the position at length, he's arguing appearances are sufficient to confer some justification for a belief in the absence of defeaters. He's got several arguments for this, but the most interesting is his view that it's actually self-defeating to deny this because any counterargument we give is ultimately going to rely on appearances as a kind of justification (see the IEP article I linked ITT for a full exposition). Now, it certainly appears to be the case that our cognitive faculties are reliable, so we are thereby justified in trusting them unless some defeater for the appearance is offered. As it relates to the retorsion argument, the problem seems to be that PSR being false doesn't satisfy either of the conditions required for an appearance being false w.r.t. the reliability of our cognitive faculties (again see the IEP article or my other posts ITT for the conditions required for a potential defeater to undermine an appearance). So, at least prima facie, it seems retorsion won't work to establish PSR against an epistemology like Huemer's. Of course, phenomenal conservatism could be wrong, but then that's another debate.

I do think Feser's arguments concerning the accounts of laws of nature do entail the PSR. At the very least, the regularity views of laws anyway (which I hear is somewhere approaching the majority view). Concerning the regularity view of laws and a hierarchical series, it seems that the critic cannot help himself to a weak version of the PSR where there are some explanations but that the fundamental laws of nature are brute facts.

I think it's an open question if you assume other accounts of laws, but still raises questions. Obviously, it's no help to the atheist to appeal to Cartsian/Newtonian theological view of laws. I'm not sure how fruitful a platonic account would be either. It would raise why the law would have the constants or platonic law rather than another or even how those laws comes to be instantiated (Feser has been through this). We may posit a brute fact at the end of the chain, but platonic views of laws seem to point towards more links in the chain, rather than being the terminus. That is hardly an easy spot for the naturalist, if the physical universe and the laws aren't available as the terminus.

I think the Aristotelian view may be the best route for the would be PSR denyer. But I'm not sure he wants to go down the route of Aristotelian metaphysics.