David Hume · Philosophy
Hume builds a science of the mind on one principle: every idea is a faint copy of a prior impression of sense or feeling. Any idea that cannot be traced to an impression is empty - a test that demolishes much traditional metaphysics.
David Hume, writing in the 1730s and 1740s, set out to do for the human mind what Newton had done for the heavens: to discover the basic principles that govern how it works, by careful observation rather than speculation. He called this the ‘science of man’ or the ‘science of human nature’, and he thought it the foundation of all the other sciences, since every science is pursued by human minds. His starting point is rigorously empirical: to understand the mind, look at what is actually in it. And what is in the mind, Hume observes, is perceptions - everything we are aware of, every sensation, feeling, thought, and idea. He then makes a simple but powerful division of all these perceptions into two kinds, distinguished by their vivacity. The more forceful and lively perceptions he calls impressions; the fainter copies of them he calls ideas. This distinction is the cornerstone of his whole philosophy. Everything that follows - his account of causation, of the self, of morality, of the limits of knowledge - is built on this analysis of the mind’s contents into impressions and ideas.
From this distinction Hume draws his central principle, often called the Copy Principle: all our ideas are ultimately derived from impressions; every simple idea is a copy of a simple impression that preceded it. We can never think of anything that we have not first, in some form, sensed or felt. The mind seems creative - we can imagine a golden mountain, or a virtuous horse, things we have never encountered - but Hume points out that this creativity is only the power to combine, transpose, augment, and diminish ideas we already have from impressions. The golden mountain is just the idea of gold (from impressions of gold) joined to the idea of a mountain (from impressions of mountains). The mind invents nothing from scratch; it only reshuffles materials that experience first supplied. To prove this, Hume offers a striking piece of evidence: a person born blind has no idea of colour, and a person born deaf no idea of sound, because they have never had the corresponding impressions. Lacking the impression, they lack the idea - exactly as the Copy Principle predicts. The mind, however inventive, is bounded by what the senses and feelings have first delivered.
With impressions, ideas, and the Copy Principle in place, Hume has laid out the programme of radical empiricism: the view that all the materials of thought come from experience, and that experience therefore sets the absolute boundary of what we can meaningfully think. There are no ‘innate ideas’ stamped on the mind at birth, no concepts that reason spins out of itself independently of the senses; whatever is in the mind got there, ultimately, through impressions. This places strict limits on knowledge. Reason, for Hume, cannot reach beyond experience to grasp the ultimate nature of reality, God, the soul, or the deep necessities that metaphysicians sought; it can only work with the ideas that experience supplies, tracing their relations and combinations. The grand systems of rationalist metaphysics - which claimed to deduce the structure of reality from pure reason - are, on this view, castles in the air, trading in ideas that have no grounding in any impression. Hume’s empiricism is thus both a constructive programme (build a science of the mind from observed perceptions) and a critical one (expose and discard ideas that cannot be traced to experience). It is one of the most rigorous and consequential applications of the empiricist principle in the history of philosophy.
This is the opening of the lesson. The rest — the dialogue, the primary source, and the recall — is in the app.
You learned that Hume divides all our perceptions into vivid impressions and faint ideas that copy them, and uses the rule ‘no idea without a prior impression’ as a test of meaning. Explain the principle and how it is used.
Leads to John Locke.
Begin this lesson →epoché — a humanities education that remembers you.