A Pocket Popper

If we can never verify a theory, only fail to refute it, then what does progress even mean? Popper's answer overturned a picture of knowledge that had held since Francis Bacon. The old story said we gather observations patiently, and general laws emerge from the accumulated facts. Popper denied this at the root. There is no such thing as pure observation, he argued; we always look at the world through some expectation, some question, some guess. Knowledge does not begin with data. It begins with a problem and a bold conjecture about how to solve it.

The pattern he proposed is deceptively simple: problem, tentative theory, attempted refutation, new problem. We throw out a conjecture — the more daring the better — and then we attack it as hard as we can. The theories that survive our fiercest attempts to kill them are the ones we provisionally keep, not because they are proven, but because they have not yet failed. Science advances not by piling up certainties but by eliminating errors. We learn what is false far more reliably than we ever learn what is true.

Popper wrote his most famous book during the Second World War, in exile in New Zealand, calling it his war effort. The Open Society and Its Enemies turned the same suspicion of certainty onto politics. He saw totalitarianism — fascist and communist alike — as the political expression of a single seductive error: the belief that someone has grasped the final truth about how society must be arranged, and is therefore entitled to impose it. Certainty in politics, he warned, licenses tyranny.

His targets were surprising. He traced the intellectual roots of authoritarian thinking back through Hegel and, more provocatively, to Plato, whose Republic he read not as a noble ideal but as a blueprint for a closed, caste-bound state ruled by philosopher-guardians who alone knew the good. Against this he set Karl Marx, whom he treated with more respect but the same firmness. Marx's claim to have uncovered the iron laws of history — historicism, Popper called it — was the same mistake in modern dress: the pretence that the future is fixed and knowable, and that resistance is merely ignorance.

Step back from the separate books and one stance runs through all of them. Popper never really changed the subject when he moved from physics to Plato; he applied the same conviction to a new terrain. Whether the question was the growth of science, the design of a state, or the workings of the human mind, his answer took the same form: we advance not by securing certainty but by exposing ourselves to error, inviting the criticism that might destroy what we believe. Fallibility was not a weakness he reluctantly conceded. It was the engine he built everything upon.

This is what makes him uncomfortable to read even now. The instinct to seek firm foundations — proof, authority, a doctrine that settles things — is deep, and Popper spent a lifetime saying it must be resisted. He offered no bedrock, no final justification, not even for his own method. He offered instead a permanent posture of critical openness, the willingness to be wrong as the price of getting anywhere at all. To think like Popper is to give up the comfort of ever being sure, and to treat that loss as liberation rather than deprivation.

The teenager who noticed that Marxism could never be caught out grew into a philosopher who made that observation the hinge of an entire worldview. Popper's line between science and pseudo-science, his account of knowledge growing through eliminated error, his defence of the open society against those who claim to know history's ending — all of it turns on the same refusal to mistake the appearance of certainty for the real thing. David Miller's compact selection lets us watch that refusal travel across a working life, from the physics of 1919 to the politics of a century in crisis.