The Chicago Philosophy Meetup

These, the best overview lectures of all time, provide a complete college course in philosophy. Beginners will get clarity and adepts will be revitalized.

Thelma Zeno Lavine’s From Socrates to Sartre: The Philosophic Quest (1978) is the most riveting (her painstaking contortionist elocution), endearing (the eerie, theremin-laced Moog soundtrack, straight from the golden age of PBS), and confrontational (her radical politics and censorship-defying critiques) philosophy lecture series ever produced.

Hume Part II; or, how to atomize philosophy into sense-data and rebuild it as psychology, so that the art formerly known as metaphysics is exposed as mental habit

David Hume’s mom described him as “a well-meanin’ critter, but uncommon weak-minded.” As everyone knows, that description could not be more ironic. Hume matured into the second-sharpest British philosopher and the fourth greatest Western philosopher of all time (according to Leiter’s 2017 poll).

While his family thought he was dutifully studying law, Hume was secretly immersed in philosophy. The breakthrough came when he absorbed Francis Hutcheson’s claim that ethical principles actually have subjective feeling (rather than divine command or rational insight) as their basis.

Hume’s radical and epoch-making move was to extend Hutcheson’s subjective feeling-ism beyond ethics to cover the domain of all knowledge generally. If moral belief arises from feeling rather than reason, then perhaps all belief—even in the sciences—does as well. On this view, so-called scientific knowledge is not grounded in objective certainty, but in our feeling that repeated sensory patterns can be trusted as truth.

If Kant was wakened by Hume’s attack on causality, Hume awoke through Hutcheson’s recognition that reason never wasthe author of moral truth, only its rationalizing scribe.

A new philosophical paradigm was arising—one that reoriented the investigation of knowledge, metaphysics, and morals toward psychological naturalism. Hutchenson —

• Extended Newton’s method into moral psychology, using the model of laws of motion to describe how ideas, affections, and moral sentiments operate.
• Treated aesthetic and moral judgments as responses of internal sense, following regularities akin to natural laws.
• Emphasized empirical access to these inner processes through introspection, not rational deduction.

What an absolutely exhilarating (and totally reasonable and intelligible) simplifying model Hutcheson had provided! Hume referred to it as a “new Scene of Thought”; today we'd call it a “paradigm shift.”

Hume’s exhilarating new philosophical outlook fused the empiricism of Locke and Berkeley—who held that all knowledge derives from sense perception—with the moral philosophy of Francis Hutcheson, who argued that morality rests not on reason or revelation, but on sentiment.

Being the logos of a new movement propelled Hume into a kind of intellectual ecstasy. In fact, the revelation was soexciting that Hume gave up law (which he’d started studying at age 12 ) and worked instead on the new scene—and so entered a six-month long manic episode buzzing with discovery, breakthrough, and feelings of great power.

But the exhilaration of his breakthrough soon gave way to anxiety and dread. In 1729, Hume suffered a severe nervous collapse, followed by five years of what we would now call clinical depression.

Convinced that his philosophical ambitions were doomed, he resolved to abandon philosophy altogether.

Yet within months, he reversed course and retreated to La Flèche, the site of Descartes’s old Jesuit college, where he feverishly composed his Treatise of Human Nature (1739).

In Praise of Reductionism

We may claim to despise reductionism, but we can never fully renounce it—because understanding itself depends on it. Intelligibility presupposes the derivation of the many from the one, or at least from a few: we are always hunting for types, root causes, schemas, archetypes—the five love languages, the single trauma that explains everything. We want the chaos of lived experience metabolized into elegant generalities. The sciences, of course, run on this fuel. Kant, recognizing this drive, called it a regulative love: reason demands that the manifold be comprehended under unifying principles, even if such unification can never be completed. This yearning for covering laws is not a vice but the very condition of understanding.

Yet hadn’t this reductionist impulse already been undertaken by Hobbes and Descartes? What distinguishes Hume’s application of “the Newtonian method” to the inner machinery of experience from these earlier mechanical models? What makes his scene of thought genuinely new?

Before Newton, Hobbes attempts to reduce human action to motion and desire (Leviathan, 1651). He explicitly models reasoning as calculation and the passions as mechanistic effects of appetite and aversion.

Descartes, in the Passions of the Soul (1649), attempts a neuro-mechanical account of emotion. But Hobbes and Descartes are still working from rationalist metaphysical premises—they posit mechanistic accounts, but they lack Newton’s empirical framework.

It is only with Locke that the method matures into something like a proper “doctrine of elements.” Locke’s Essay is the first great attempt to reduce mental operations to a finite set of faculties (sensation, reflection, comparison, etc.), with ideas built up from sense data. He rejects innate ideas and insists on an empirical model of the mind, but he is not yet modeling the mind as governed by laws in the Newtonian sense.

The Humean Anthropological Turn

Hume will reduce human mental life to a few simple principles. But why is he going to do this? It is because all other sciences are based upon the science of man. Therefore to study the science of man, the science of human nature, is really to study the foundation of all human knowledge. The idea is simple: since all access to reality is mediated by the mind, a systematic account of how the mind operates offers, in principle, a synoptic understanding of the conditions under which reality becomes knowable at all. The study of human nature is actually a metacritical study of all knowability generally.

Hume begins his Treatise with a modest taxonomy: all contents of consciousness are either impressions (lively, sensory, immediate) or ideas (fainter copies derived from impressions). From there, he develops an argument:

1. Every meaningful idea must be traceable to a prior impression.
2. If no such impression can be found, the idea is meaningless.
3. Therefore, metaphysical notions—substance, mind, self—turn out to be empty shells, linguistic husks inherited from tradition but devoid of empirical content.

In the Enquiry (1748), this becomes not just an epistemic principle but a criterion of meaning, similar to the later empiricist semantic verificationism of Ayer and the logical positivists. Hume’s rule is simple, brutal, and final: no impression, no idea; no idea, no meaning.

And with that, centuries of rationalist metaphysics are swept aside.

Hume does not stop at demolishing metaphysics. He reconceives the very mechanism of thought. The mind, in his view, does not reason in the traditional sense—it associates. Impressions and their ideas are atomistic, discrete, and inert, unless animated by three “gentle forces”: resemblance, contiguity, and cause-effect. These psychological principles—not logic—explain how we move from one idea to another, even in science.

Of these, causation is the most consequential. And it is here that Hume’s assault on Enlightenment rationality is most devastating.

Science as Feeling

Scientific knowledge, Hume argues, rests on causal inference. But we never perceive causal necessity; we only perceive constant conjunctions—fire regularly followed by heat, wounds followed by pain.

There is a glueiness of the mind that puts ideas together when the same impression is repeated often enough. But this glue doesn’t flow from logical necessity. It comes from … elsewhere. For Hume, the womb of these apparently in-world connections is our own expectational feeling. The feeling of outer necessity is just that—a feeling, born of custom.

The upsetting conclusion: the laws of physics are not objective features of nature but subjective psychological habits. What we call science is simply an ordering of impressions through mental association, accompanied by a sentiment of compulsion.

In other words, as Thelma so pungently puts it, physics is psychology. Newton’s laws, the crown jewels of Enlightenment reason, are demoted to complex regularities we happen to expect. A nightmare for scientific realists and all normals generally.

Bonus Observation: Hume as Proto-Kantian Rationalist

In addition to tracing the standard destroyer narrative, we’ll also explore Hume’s incipient metaphysical constructivism. While Hume never explicitly endorsed a second kind of necessity, he did note the mind’s innate ability to lock onto causal patterns in nature. It’s just that his explanations of what the causation amounts to had to do with the mind projecting itself onto those non-coincidental unities, something he was not inclined to call necessary.

If Hume stopped short of calling this “necessity,” Kant would not: Here, Kant will say, is the missing piece—a form of necessity rooted in the mind’s ability to recognize non-coincidental regularities through perception, imagination, and innate spatiotemporal structure.

Hume thus occupies a position far closer to Kant than the traditional narrative allows. His empiricism, expanded to include memory, imagination, and the mind’s structuring activity, begins to look less like skepticism and more like a mitigated rationalism.

If rationalism is all about defending the formal sciences and the natural sciences—and modal grounds of both—then Hume is, in that sense, a rationalist.

This arc—from Locke through Hume to Kant—can be seen as the gradual emergence of a theory of non-logical necessity, grounded in primary qualities and the mind’s capacity to track them. Locke’s search for the mental faculties that correspond to nature’s objective structure anticipates Kant’s claim that experience is intelligible only because the world must conform to the forms of our judgment. Hume occupies the inflection point: a proto-structuralist of sensibility whose analysis of causal connection—though framed in terms of habit and feeling—exposed the need for a deeper account of the mind’s role in constituting necessity. In doing so, he provided the very problem-structure that would allow Kant to reconceive metaphysics on new, transcendental grounds.

METHOD

Please watch the tiny 27-minute episode before the event. We will then replay a few short clips during the event for debate and discussion. A version with vastly improved audio can be found here:

We'll be starting at Book III, 676a (the previous meeting started at Book II, 671b)

The dramatic action is as follows: three elders - an Athenian, Spartan, and Cretan - walk the path of Minos and discuss laws and law-giving.