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Thinkers

David Hume

1711–1776, Edinburgh

British Empiricism

Reason is far weaker than we think, and habit does most of the work.

Problem of inductionCausation as constant conjunctionBundle theory of selfIs–ought gap
“Reason is, and ought only to be the slave of the passions.”
A Treatise of Human Nature II.3.3

The life

Hume was born in Edinburgh and sent to university at about eleven. He was pushed toward law, abandoned it, and had some kind of breakdown in his early twenties while working obsessively on his own system.

He wrote A Treatise of Human Nature in France, at the Jesuit college of La Flèche where Descartes had studied, and published it at twenty-eight. It failed completely. In his own phrase, it fell dead-born from the press.

He was twice refused a university chair on suspicion of atheism, and made his living as a librarian, tutor, secretary and finally as a historian: his History of England was a bestseller and made him wealthy. In Paris he was a celebrity of the salons, and he brought Rousseau to England in a friendship that collapsed spectacularly. He died of abdominal cancer, cheerful and unrepentant to the end, which disturbed Boswell considerably.

What shaped the ideas

The Scottish Enlightenment took Newton's success as a model and asked whether the same experimental method could be applied to the human mind. Hume's subtitle for the Treatise says exactly that: an attempt to introduce the experimental method of reasoning into moral subjects.

The result was more corrosive than he intended. Applying strict empiricism to causation, the self and induction dissolved the foundations that everyone assumed were secure, and Hume followed the argument rather than the expectation.

Core arguments

  1. 01

    The problem of induction

    Nothing justifies the assumption that the future will resemble the past.

    Every inference from observed to unobserved cases relies on nature being uniform. That assumption cannot be proved by reason, since a change in the course of nature involves no contradiction. It cannot be proved by experience either, because that argument would already assume the uniformity it is trying to establish. So the belief has no rational foundation, only habit.

  2. 02

    Causation as constant conjunction

    We never observe necessary connection, only repeated succession.

    Watch one ball strike another as many times as you like: you see contact, then motion. You never see the necessity linking them. What supplies the sense of connection is the mind's habit of expectation after repeated pairings, which we then project onto the world.

  3. 03

    The bundle theory of self

    There is no enduring self to be found, only a bundle of perceptions.

    Every time he looks inward he finds a particular perception: heat, cold, pleasure, pain. He never catches a self having them. If the self were a genuine impression it would be constant, but nothing in experience is. So the self is a bundle in rapid succession, held together by memory and resemblance.

  4. 04

    The is–ought gap

    You cannot derive a conclusion about what ought to be from premises about what is.

    Moral arguments proceed through statements of fact and then, without notice, switch to statements with "ought" in them. Since "ought" expresses a new relation, it needs to be explained, and no set of purely descriptive premises entails it. Hume flags this in a single paragraph and moves on.

Commonly got wrong

  • Hume is not a practical sceptic. He says explicitly that nature cures the doubt: you leave the study, play backgammon, and the arguments lose their grip. His claim is about what reason can justify, not about how to live.
  • "Reason is the slave of the passions" is not a licence for irrationality. It is a claim about motivation: beliefs alone never move anyone to act; a desire has to be present, and reason works out how to serve it.
  • The is–ought passage is one paragraph, and how much it proves is genuinely contested. Reading it as a knockdown proof that ethics cannot be grounded goes well beyond what Hume wrote.

Works

  • A Treatise of Human Nature 1739–40

    The full system, written at twenty-six. Ignored on publication, now his most studied work.

  • An Enquiry Concerning Human Understanding 1748

    The Treatise's epistemology, rewritten to be readable. This is the one to start with.

  • An Enquiry Concerning the Principles of Morals 1751

    His own favourite. Sentiment and utility as the basis of moral judgement.

  • Dialogues Concerning Natural Religion 1779

    Held back until after his death for good reason. Takes apart the argument from design.

The first Enquiry, Sections IV and V, on induction and custom. About twenty pages and completely self-contained.

Why they still get taught

He set the problems analytic philosophy is still working on. Induction, causation, personal identity and the fact-value distinction are all live because Hume framed them, and cognitive science has largely vindicated his emphasis on habit over reasoning.

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