I don’t do contemporary philosophy so I have no idea how everyone became convinced that the definitive character of the intelligible/ abstract (IA) is being non-causal. Uncharitably, I assumed it was some weird collective madness that would blow over. I still think it will, because the problems with the claim are legion. Here’s a few:
1.) It’s obviously false. The IA causes knowledge and therefore causes anything that knowledge does. Just how far knowledge is causal is an open question, but it falls somewhere between causing some human actions to causing all events in the universe.
The IA causes science, indignation, insight, revolutionary ideals, making recipes, etc. as a formal cause or as a material component in a larger system. I take it as obviously false to say that this is not bona fide causality, but even if one restricts “causality” to mean “agency” there are still problems like:
2.) The IA is not a logical predicate in spiritual agents and so has real agency. God is his divinity, an angel is his own species, and at the height of human existence the distinction between the purely formal and the individual breaks down. My IA are both wholly mine and yet the same as the ones you know. When Aristotle speaks of the making intellect at the height if human personality he is forced to speak of as that which is purely individual (since it is a part of the individual soul) and yet generative of a world common to all human persons, past and future. The Averhoists were not entirely wrong in arguing for a single agent intellect for all persons – the agent intellect as a real purely formal character even if it is not formal in every way an angel or divinity is, and this purely formal character makes it communicable to all persons, past and future. But St. Thomas’s insight was the more crucial one – the formal character of the agent intellect is essential to the dignity of the person.
But back to some more down to earth problems like
3.) The claim is anti-teleological. All teloi have intentional existence and so arise from intellect either immediately or by participation. In teleological or axiological accounts, the goal is not just a cause but what most of all deserves to be called the cause. When teleology or axiology is in play, it would be truer to say that the IA is the most causal.
4.) It’s against even the broadest and most general elements of the Platonic tradition. Plato himself clearly thinks that the IA is the most causal of all things – Socrates’s speech in the development of his ideas of causality at the end of Phaedo tells of rejecting any account of causality that doesn’t trace it back to the IA. But even the broadest and loosest account of the Platonic tradition (From the Augustinians to Malebranche to Galileo and Newton to Carl Jung) posits the causal supremacy of the IA, whether through the eternity of the ideas or the mathematical-abstract character of the truly real or the positing of governing archetypes.
I am pressed for time and have to stop here, but there’s a good deal more to say…