Sir Karl Popper was one of the most influential philosophers of the twentieth century. His contributions to philosophy of science, political philosophy, and epistemology are immense. The most visible signs of Popper's importance are the countless references to him or his work in various media, including university curricula, throughout the world. Moreover, he has been second to none in earning as much respect outside the profession of philosophy as within it; Chancellor Helmut Schmidt, Sir Peter Medawar, Friedrich Hayek, Sir John Eccles, and Sir Ernst Gombrich, to mention but a few, were ardent Popperians. Yet Popper's work has not prompted that cottage industry of books and articles which surrounds, and often buries, the work of other equally influential philosophers, notably his countryman Ludwig Wittgenstein. This is partly due to his clarity of writing, inviting almost no questions of the precise meaning of what he says. Another equally important factor is Popper's autobiography, Unended Quest, which tells the genesis of his ideas, again so clearly as to raise almost no further historical questions. But as his recent and first intellectual biography, by Malachi Hacohen, has demonstrated, providing a greater context may contribute to a better understanding of even Karl Popper.

This book is not an intellectual biography. Its focus is on a specific aspect of Popper's philosophy: the nature and genesis of his evolutionary epistemology.