Professor Munz examines and rejects the Wittgensteinian position. Instead, Our Knowledge of the Growth of Knowledge, first published in 1985, elaborates the potentially fruitful link between Popper’s critical rationalism and Neo-Darwinism. Read in the light of the latter, Popper’s philosophy leads to the transformation of Kant’s Transcendental Idealism into ‘Hypothetical Realism’, whilst the emphasis on the biological orientation of Popper’s thought helps to illumine some difficulties in Popper’s ‘falsificationism’.