Karl Popper · Philosophy
Popper’s answer to Hume’s problem of induction: science does not build knowledge by generalizing from observations at all. It grows by <em>conjecture and refutation</em> - bold guesses, ruthlessly tested and weeded out - so that knowledge advances not by proving theories true but by eliminating the false.
There is a comfortable story about how science works, and Popper spent his life demolishing it. The story - call it inductivism - says the scientist begins by observing the world with an open mind, gathers a great many facts, and then generalizes from them to laws: enough white swans, and you conclude that all swans are white. Knowledge, on this view, is built up from experience by induction, from the particular to the universal. Popper thought this was a myth from beginning to end. There is no such thing as pure, theory-free observation; to observe at all you must already have a question, an expectation, a point of view - told simply to ‘observe,’ you would have to ask ‘observe what?’ And even if we could gather bare facts, no logical road leads from ‘some’ to ‘all.’ Science, Popper argued, does not start from observations and crawl up to theories. It starts from problems, and from bold theories freely invented to solve them.
Popper’s starting point was a problem David Hume had posed in the eighteenth century and that no one had solved. We constantly reason from experience: the sun has risen every day, so it will rise tomorrow; this bread nourished me, so the next loaf will too. But what justifies the leap? Hume showed there is no valid logical argument from past instances to future ones, because it is never self-contradictory to suppose the future will differ from the past. Nor can experience justify the leap without arguing in a circle, since ‘experience has always worked before’ is itself just another inductive inference. Hume concluded that our inductive habits rest not on reason but on custom - a psychological compulsion to expect the familiar. Popper found Hume’s logic unanswerable and his psychology a counsel of despair: if the whole edifice of science really rested on nothing better than habit, reason itself was bankrupt.
This gives Popper’s whole picture of the growth of knowledge, from the amoeba to Einstein. Life confronts problems; an organism, or a scientist, responds with a tentative solution, a conjecture; that conjecture is then tested against reality, and its errors are eliminated; the surviving, corrected conjecture throws up new problems, and the cycle begins again. Knowledge grows not by accumulating certainties but by successive approximations - by making mistakes and learning from them. Every theory is a net cast to catch ‘the world’, and we make the mesh ever finer as our theories are refuted and replaced by bolder, better-tested ones. Progress is real, but it is progress from error, not toward certainty. The scientist differs from the amoeba not in escaping error but in actively seeking it out: consciously criticizing theories, trying to kill them, so that the theory dies in our stead.
This is the opening of the lesson. The rest — the dialogue, the primary source, and the recall — is in the app.
You learned that Popper accepted Hume’s point that induction cannot be logically justified, and drew a radical conclusion: science never uses induction, but advances by conjecture and refutation - proposing bold theories and eliminating those that fail our tests. Explain why Popper thought there is no induction, and h…
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