There’s no confusion here since I’m familiar with Aristotle’s philosophy. I’m aware also of how his view of nature has been superseded by the scientific revolution. Aristotle’s philosophy was too anthropocentric since he presumed that because human-made artifacts have purposes (“final causes”), everything else must have them, and he assumed as much even as he eliminated creator gods from his world picture.
You say, “natural law analysis is about the essence of something, while biology is about the accidents of the thing.” But if that analysis is supposed to be a priori, meaning that it’s conducted from the armchair, it’s open to bias. Thus, conservatives, for instance, will posit one human form, while liberals will posit another. Who’s to say which description is best if they’re both expressions of different attitudes and outlooks? Scientists bypassed that kind of academic metaphysical dispute and studied the patterns with their senses. The more empirical research they conducted, the more wild, inhuman, and amoral nature seemed.
This means that whatever metaphysical gloss you want to impose on patterns--calling them formal or final causes or positing metaphysical essences or natures--that “data” won’t entail any moral value. Hence the natural law theory of morality is fallacious and a dead end.
Heterosexuality evolved as a strategy for reproduction, that is, for the transmission of genes. That’s sex’s natural, evolved function. But that doesn’t mean we’re morally obligated to defer to that function. Why? Because human nature is free. That’s what makes people different from animals. Consequently, we’re not morally bound by our “metaphysical form.” Existence precedes essence in our case, as Sartre said. We establish our nature because our nature is paradoxical in being free. For instance, we can emphasize the reproductive function of sex, if we like, or we can focus on the orgasm. Or we can bypass the sex act and reproduce artificially, thus enabling homosexuals to have families.
Where did homosexuality come from, according to Catholicism? It’s a sinful choice, surely, from that perspective. So Catholics posit the very freedom that makes nonsense of the Aristotelian natural moral theory, just as that theory contradicts the original sin doctrine, as I said. Once again, then, none of this article’s objections is affected by your leaning on the metaphysical Aristotelian rhetoric. You’re only quibbling about terminology.
