Hume

David Hume (1711–1776) was a Scottish philosopher and the most radical empiricist of the Enlightenment. He pushed empiricism to skeptical conclusions that are still central to philosophy today — about causation, the self, induction, and the foundations of Ethics.

Life

Born in Edinburgh, Hume showed exceptional intellectual precocity. His first major work, A Treatise of Human Nature (1739–40), fell "dead-born from the press" by his own account. He later revised its arguments into more accessible essays and enquiries, which brought him fame and controversy. His Dialogues Concerning Natural Religion (1779, published posthumously) remains a landmark of philosophy of religion. He worked as a librarian, diplomat, and historian, and died contentedly — his equanimity in the face of death impressing his friends and scandalizing religious contemporaries.

Empiricism and the Theory of Ideas

Hume's Epistemology begins with a strict empiricist principle:

Impressions — vivid, direct sensory and emotional experiences
Ideas — faint copies of impressions (what we think about)

Any philosophical concept that cannot be traced back to an original impression is meaningless. This is Hume's "fork" — a powerful tool for demolishing speculative Metaphysics.

The Problem of Causation

Hume's most influential argument: we never perceive necessary causal connection.

When we say "fire causes heat," all we ever observe is:

Spatial contiguity (they are near each other)
Temporal succession (fire precedes heat)
Constant conjunction (they always occur together)

We never see the necessary link between cause and effect. Causation is a habit of mind — a psychological expectation based on past experience — not a feature of the external world. This deeply influenced Kant, who said Hume woke him from his "dogmatic slumber."

The Problem of Induction

Even more radically: past experience gives no logical guarantee about the future. The inference "the sun rose every day before, so it will rise tomorrow" is not logically valid. This is the problem of induction — one of the most persistent problems in Epistemology and philosophy of science.

The Bundle Theory of Self

Hume denied the existence of a persistent, unified self. When he introspects, he finds only a "bundle" of perceptions — sensations, emotions, thoughts — in rapid succession. There is no additional "self" that has these perceptions. This challenges Descartes' cogito and shaped Kant's response.

Ethics: Reason and Sentiment

Hume argued that reason cannot motivate action — it merely informs us of facts and connections. Moral judgments are expressions of sentiment, not rational cognition:

"Reason is, and ought only to be the slave of the passions."

This is moral sentimentalism — a direct challenge to Kant's rationalist ethics. Moral approval and disapproval are rooted in our natural sympathy for others.

Hume also formulated the is-ought gap (Hume's guillotine): you cannot derive an ought (normative claim) from an is (descriptive fact) alone. This challenged both divine command theory and natural law ethics. See Ethics.

Philosophy of Religion

Hume's Dialogues systematically dismantled the argument from design (the world looks designed, so there must be a designer). He also argued that testimony for miracles can never rationally outweigh the overwhelming evidence from uniform experience that such events do not occur.

Influence

Kant's entire critical project is framed as a response to Hume
Logical positivism (20th century) adopted Hume's empiricist principle as its "verification criterion"
Contemporary philosophy of science still grapples with the problem of induction
Wittgenstein engaged deeply with Hume's questions about following rules and the limits of justification

Epistemology — empiricism, induction, and the limits of knowledge
Metaphysics — Hume's skepticism about causation and substance
Ethics — reason vs. sentiment; the is-ought gap
Kant — who responded directly to Hume's skepticism
Descartes — whose rationalism Hume undermined
Locke — the empiricist tradition Hume pushed to extremes
Consciousness — Hume's bundle theory of the self
Political Philosophy — Hume on justice as artificial virtue