Karl Popper, a philosopher and ex-communist, criticised thinkers from Plato to Marx who valued the collective over the individual.

ECONOMIST: How three Viennese thinkers changed the world

Karl Popper, a fellow Austrian-born academic, advised him to insist on a small additional royalty which he has never regretted.

ECONOMIST: Look and learn

Karl Popper was not always forthcoming about his early life and his early intellectual trajectory may surprise some of his admirers.

ECONOMIST: Non-fiction

The answer comes from the eminent philosopher of science Karl Popper: falsifiability.

FORBES: The Confidence Game

The moral weight of Karl Marx's criticisms of 19th-century capitalism even won him praise from the high priest of Western liberalism, Karl Popper, a Viennese-born philosopher who emigrated to London.

ECONOMIST: Mankind��s biggest mistake

As thinkers like Milton Friedman, Friedrich Hayek or Karl Popper, and indeed the amazing death toll of communism itself have shown, coercion and violence are deeply embedded in that ideology.

ECONOMIST: Letters | The

He calls them Black Swans, after the philosopher Karl Popper's observation that only a single black swan is required to falsify the theory that "all swans are white" even when there are thousands of white swans in evidence.

WSJ: Shattering the Bell Curve