I don't think this chain of reasoning is consistent with Hume's.
Hume is an empiricist, not a nominalist: he doesn't deny the existence of abstract categories, only their a priori intelligibility. He also makes direct reference to non-physical, desirable things (it's been a while, but I'm pretty sure approbation and praise are his chief examples). We're ruled by our passions not because our ends are always physical, but because (according to Hume) (1) reason alone cannot lead us to action and (2) we clearly are lead to action all the time. Therefore, something else must be driving us.
At any rate, it seems to be all part of the same package, at least to me.
As a side point, I've noticed that pretty much all these cutting edge, modern ideas that we believe have overthrown the ideas of the past were all around at the same time as Plato. In fact, a number of dialogues deal with debating concepts such as relativism, scientism, Nietszche's will to power, Kant's idea that we are trapped by mental constructs, etc. Intelligent design was even a big thing, and apparently was what started Socrate's on his philosophic quest.
Reading through modern philosophy strikes me as pretty mundane, and it seems as if these modern philosophers were really myopic and either never read classic philosophy (most probably did) or just picked out the pieces they liked and ignored the counter arguments. Then they get paraded around as if they are brilliant innovators to an audience that doesn't know any better.
Hume argues explicitly for free will via compatibilism. The SEP has an excellent summary of the argument[1], but in sum: what matters for moral responsibility is hypothetical liberty. Our ability to will (undisputed by Hume) grants us HL.
The interplay being passions (physically ended or otherwise) and voluntary/involuntary action in Hume's account is complex and can't be accurately reduced to a deflation of free will.
> As a side point, I've noticed that pretty much all these cutting edge, modern ideas that we believe have overthrown the ideas of the past were all around at the same time as Plato. In fact, a number of dialogues deal with debating concepts such as relativism, scientism, Nietszche's will to power, Kant's idea that we are trapped by mental constructs, etc. Intelligent design was even a big thing, and apparently was what started Socrate's on his philosophic quest.
I think this is a misapprehension of Modern (i.e., 17th to 19th century) philosophy. Modern philosophy is explicitly a rediscovery and re-evaluation of Classicial philosophy, having been largely lost to (or dogmatized within) the Western world. Overarching ideas follow suit; Hume, Kant, et al. make explicit reference to their forebears. And that's not to say that Modern philosophy lacks in innovation: there is no appreciable equivalent to Kantian duty, Millian global happiness, Cartesian skepticism, &c in Classical philosophy. Modern political theory doesn't exist without natural law, &c.
FWIW, I don't think that "scientism" is an intelligible subject within modern philosophy: it's only within contemporary philosophy that we've really begun to develop a formal account of what science actually is. Hume, Kant, and contemporaries don't have a rigorous concept of science discrete from the general practice of philosophy in the natural domain.
Similarly for Socrates and intelligent design: I'm guessing you're referring to his teleological claims. But keep in mind the historical context: the Greek religion was explicitly concerned with dividing the natural world into the domains of anthropomorphic gods, and Hesiod's Theogony was already 200+ years old by Socrates' time. Given this and his reference to pre-Socratic thought on teleology, it's unlikely that he had anything resembling contemporary creationism in mind.
> Reading through modern philosophy strikes me as pretty mundane, and it seems as if these modern philosophers were really myopic and either never read classic philosophy (most probably did) or just picked out the pieces they liked and ignored the counter arguments. Then they get paraded around as if they are brilliant innovators to an audience that doesn't know any better.
What audience? I was educated in philosophy, and I certainly wasn't taught (or primed) to treat Modern philosophers as brilliant innovators in contrast to Classical philosophers. On the contrary: both groups were held in extremely high regard, and Classical philosophy remains central to contemporary ethics (see Anscombe, Arpaly, and other revitalizers of virtue). Formal logic is introduced with Aristotle. Ontology is introduced with Plato.
In any case, it's important to not interpret the different eras of philosophy as existentially clashing with or ignoring the others. The history and development of philosophy is a unified one.
I've seen quite similar concepts to the ones you mention re: Kant, Mill, Descartes, etc in different Platonic dialogues. So, they are maybe micro innovative, but not in a big picture sense.
By "intelligent design" I mean Socrates began his quest looking for a philosopher that could explain the world in terms of 'why' orchestrated by an overarching mind, instead of 'how'. From Phaedo,
"One day I heard someone reading, as he said, from a book of Anaxagoras, and saying that it is Mind that directs and is the cause of everything. I was delighted with this cause and it seemed to me good, in a way, that Mind should be the cause of all. I thought that if this were so, the directing Mind would direct everything and arrange each thing in the way that was best."
Socrates goes on to find out Anaxagoras is blowing smoke, and in general is displeased with the scientism of his day, where everyone explains the world in terms of 'how' instead of 'why'. So, he then goes about questioning all the contemporary philosophers to see if any are able to articulate the kind of explanation he's looking for, and for the most part (except for Diotima) they are unable to give a satisfactory explanation.
I think you've said something similar before, but it's a dubious claim. Philosophers spend their lives figuring out what we "really mean" when we use certain terms, and most of them are inclined towards a compatibilist interpretation.
Going back to when you brought up free will (I'm still not sure why you did!), instead of saying
> In that case he seems to not believe in free will
for clarity, you should have said
> In that case he seems to not believe in libertarian free will
But this is a given. Determinists generally do not believe in libertarian free will.
Going back to something you said previously, could you point m in the direction of where Epicurus has written similar ideas to Hume's?
https://plato.stanford.edu/entries/epicurus/ "The function of the human mind — that part of the soul that is located in our chest — is not to seek higher things, but to maximize pleasure and minimize pain. That is its entire objective; the risk (a substantial one) is that it may miscalculate, since it is subject to false beliefs and errors in cognitive processes."
Based on that article I would say Hume's overall body of work is by a wide margin more contemporary than Epicurus' if not more subtle and sophisticated. The passions-slave-reason quotation is really only a tiny part of his writing. For example, Hume provides an intricate and judicious account of epistemology in which causality is reduced to a kind of anthropic pattern-recognition. This reconciles his account of psychology with the enlightenment understanding of the scientific method, which did not exist at the time of Epicurus.
Nominalists, such as Hume, don't believe there is such a thing as 'good itself', and believe all mental abstractions are merely labelings of physical things. Thus, mental abstractions cannot be the goal of our desire. Only physical things can be the goal of our desire, and we must necessarily be ruled by our passions. Note, this was not an innovation on Hume's side. A number of philosophers before and during Plato's time proposed similar ideas, such as Epicurus. So, we cannot say Hume came up with a brilliant idea no one had ever considered before. However, for whatever reason, most of the philosophers of the Western canon sided with Plato rather than with Hume. Perhaps because Plato was closer to the truth than Hume.