Well, at least on the surface Aquinas simply glosses free choice as the ability (or corresponding act) to do otherwise, exempli gratia. For that reason, while Aquinas of course thinks the beatific vision is superlatively great, the willing involved in it is not something he would call free. Choice is only of means, not ends, so free choice is only of means, not ends.

But here are some qualifications: That Aquinas glosses freedom as the ability to do otherwise does not on its own show that he is a libertarian rather than a compatibilist. For the question is what kind of modality is involved here, and he never articulates a conception of determinism against which a modern libertarian would define free choice as not determined. And I wouldn't deny that ultimately some kind of "freedom as excellence" conception of free will can be extracted from Aquinas, but I think this involves projecting a different use of "free" onto him; it's not the way he uses the term, I think because he does not have the anxieties of contemporary libertarians.

My own belief, stated dogmatically, is that Aquinas is a libertarian, because he thinks there are cases where precisely the same apprehension of competing goods can issue in diverse actions, but his ground for the view is not the principle of alternative possibilities, as it is for many contemporary libertarians, because he does not quite hold that principle.

I don't think Feser has fully staked out his views on the matter, but my sense is that he is sympathetic to the Dominican (Banez, Garrigou Lagrange) views on nature and grace, which turn out to be fairly compatibilist. But all of that is above my pay grade.
 

Welcome to the forum.

We can speak of necessity accruing either to facts or to descriptions/sentences/propositions. The latter are representations of the former; facts are something concrete.

When we speak of 'truths,' it's ambiguous between these two categories. Sentences, for instance, can be true or false, and when they are true, it makes sense to speak of the facts to which they refer as truths.

I think you're right that necessary truths in the sense of descriptions/sentences do not explain anything, but it may still be that the necessary facts which correspond to them do explain things. For instance, if God exists necessarily, then the fact that he exists is necessary and explains things. So I don't think it will be enough to rule out that necessary truths in the sense of necessary descriptions/sentences are explanatory (because your interlocutor's argument would be best if he meant something else) and I don't think it is possible to rule out that necessary truths in the sense of necessary facts are explanatory (because you want to show that one of them is).

I am not sure what to say. I would revisit the argument you are presenting and see whether it implies the existence of a being with some of the properties God has traditionally been taken to have; if it does, then you should be able to find some reply to your interlocutor.

I'd also note that there 'explanation' seems to be ambiguous, and we can't expect a principle of sufficient reason to hold for every sense of the word. The fact that a circle cannot be squared can, I think explain some things, like Bob's failure to square the circle. And arguably some mathematical truths (first mathematical principles, if there are such things) explain others. And in, e.g., scientific inquiry we speak of 'inference to the best explanation'--as though there were more than one! I personally suspect that if there is a defensible version of PSR, it will be appealing to a distinct though of course related sense of 'explan

Brian wrote:

2) It's fairly clear that the good isn't pleasure in any standard way.  I can always ask, "Is this pleasure I am receiving good?"  Me asking that question demonstrates that, at least at a conceptual/linguistic level, we differentiate between pleasure and goodness.

This is G.E. Moore's argument, but I think it hangs on an intuitive but ultimately unsustainable understanding of meaning. One would think that if you know what "good" means and know what "pleasure" means, then you must know that they mean the same thing, if indeed they do mean the same thing. So then it would not make sense to ask the question of whether this pleasure I am receiving is good, because anyone who could understand this question (knew what the terms mean) would know that this is not an open question.

But I can intelligibly ask "Is Mark Twain Samuel Clemens?" and "Is this water H2O?" That an identity statement holds can be something I learn. It holds necessarily if both terms are rigid designators, but it is intelligible to ask whether it holds because I can use the terms knowledgeably without knowing that they rigidly designate the same thing.

Utilitarianism can take several forms, but I think there are a number of rather strong arguments against it. The breezy use of abstract terms like "the greatest good [sometimes: for the greatest number]" conceal the sheer number of options here and gloss over the fact that for utilitarianism to do what it's supposed to, a lot of arbitrary points have to be decided.

1) Incommensurability, as John mentioned. If we compare two goods, for instance, there needs to be an answer to the question of which one is better. This is not just a point about vagueness, that assuming these questions to be generally good, we might have cases where it is indeterminate which of two things is better. You can see this where the enjoyment of two goods is roughly quantifiable. Suppose the question is whether A or B is better. If it is suggested that the only reason we can't say is that it is vague (as saying which of two people, with slightly different hair patterns and hair lengths, has less hair, might be vague), then just consider whether A or C is better, where C is a prolonged enjoyment of B. If such comparisons are in fact quantitative comparisons, then such a device should be able to remove concerns about vagueness, but they don't, for there will be cases where the comparison between A and C is also impossible to make.

2) "The greatest good for the greatest number" contains a double comparative which requires disambiguation to single out a determinate state of affairs. For if you just choose the slightly better outcome for the most people, you can get what one would intuitively regard as result inferior to a far better outcome for a slightly smaller number of people. (this argument is due to Geach)

3) If you cut out "for the greatest number," and just try to talk about "the greatest good" or "the total of all goodness," then you will have to decide how this number is to be computed. The various options all seem to fit poorly

I became Catholic after spending my adolescence and teenage years as an atheist.

My 'reasons' included the witness of some Catholics I knew and of the Church throughout history, as well as a general dissatisfaction with my secular ethical outlook, which 'combusted' as it were as I was reading War and Peace and Ulysses.