Few philosophers in this century have had either Karl Popper's range or his influence, inside and outside philosophy. This collection of essays by fifteen distinguished philosophers, several of whom have been closely associated with Popper and his work, provides a timely assessment of Popper's contributions in a number of key areas: the methodology and philosophy of science; probability and determinism; quantum theory; biology; the theory of evolution; and the theory and practice of politics. The volume offers the specialist and the general reader alike fresh insights into the life and work of one of the twentieth century's most original thinkers.