Categoricals come from Michael Thompson fairly recently. Aristotle coins the term essence, in the Greek “what it was to be” (to ti en einai), just as a matter of geneological clarification. I have never seen anyone try to claim that Aristotle wasn’t an essentialist. What is argued over (endlessly) is the extent to which Aristotle can be called a Platonist (which he can be in some ways and not others).
Anyhow, I guess what stands out to me is that saying that categoricals are “inherently both descriptive and yet normative” and that “normative standards emerge from the pattern of living things” is not obviously a non-metaphysical or non-essentialist account of goodness. Thompson’s categoricals are originally there to enable a naturalistic account where organisms as wholes are prior to anything the language community is saying about “what counts as x.” The categorical “wolves hunt in packs” is supposed to track something real about the nature of wolves; the categorical does not constitute such a nature. Rather, the “normativity” (measure of “goodness for”) flows from the life-form. This is, in context, a biological fact about a kind, not a linguistic delineation. When a wolf fails to hunt effectively, it is defective because of what wolves are, not because of what men say wolves are
So, perhaps you could adapt something like the categorical to your own commitments and find use for them, but their original framing is precisely a context where the ontological reality of the organism is prior. I am pretty sure I have seen the logical form of the categorical adopted to forms of linguistic idealism before, but that would be a very different reading.
Anyhow, we still need an account of why this characteristic organic pattern is normative (i.e., good). So it seems we still need either:
A. Something like a teleological nature; or
B. A purely statistical/functional account (which Foot explicitly rejects as insufficient).
To the extent that one allows an is/ought gap, it is unclear how it is ever crossed here without an appeal to A. B does not get us here. But note that there are purely immanent explanations of teleology (or something like it), so this doesn’t obviously require throwing around the adjectives “divine” or “eternal” per se.
But to your earlier point about “seeing” values from facts, without them “following:” Hume’s famous argument in the Treatise supporting the gap at the opening of Book III is precisely that one can never see vice and virtue, in the same way that one never observes causes. Virtue and vice, and causality, are extrinsic subjective imputations.
Of course, the counter is that seeing a rock smash a window just is seeing causality, and seeing a vile act just is seeing evil, and that Hume’s entire argument rests on the dogmatic assertion of allocating some elements of experience to the subjective realm, and others to the objective.
The gap exists because of the anthropology presupposed, to quote the man himself:
Since morals, therefore, have an influence on the actions and affections, it follows, that they cannot be derived from reason; and that because reason alone, as we have already proved, can never have any such influence. Morals excite passions, and produce or prevent actions. Reason of itself is utterly impotent in this particular. The rules of morality therefore, are not conclusions of our reason.
No one, I believe, will deny the justness of this inference; nor is there any other means of evading it, than by denying that principle, on which it is founded. As long as it is allowed, that reason has no influence on our passions and action, it is in vain to pretend, that morality is discovered only by a deduction of reason. An active principle can never be founded on an inactive; and if reason be inactive in itself, it must remain so in all its shapes and appearances, whether it exerts itself in natural or moral subjects, whether it considers the powers of external bodies, or the actions of rational beings.
It would be tedious to repeat all the arguments, by which I have proved, that reason is perfectly inert, and can never either prevent or produce any action or affection, it will be easy to recollect what has been said upon that subject. I shall only recall on this occasion one of these arguments, which I shall endeavour to render still more conclusive, and more applicable to the present subject.
This is the begining of Book III. The reason that we can never derive ethics from descriptions, for Hume, flows from his anthropology. I should note that when he says he has “already proven” reason is inert, this is Book II. Part III. Sect 3., and it amounts to him dogmatically asserting this is so. Hume really has no comparative phenomenology or historical overview to support this assertion, he takes it as true because it’s already a popular idea in his context and runs with it essentially unargued. But it is precisely this unargued point that is so critical to the gap. This point, however, presupposes something like the original use case for categoricals is false. You can never tell what is good for something by knowing what it is, because knowing and feeling are mutually exclusive, one targeting the subjective, the other the objective. They never mix. If they did mix, you don’t have the gap in the first place.
) but I believe that is a separate step or movement, one that is not necessitated by the acknowledgment of the levels 1 and 2 statements.