In the first place, Hans Albert is famous as the spokesperson of Karl Popper's critical rationalism in the German-speaking world. This is chronologically a bit odd, given that Popper's first vintage, his Logik der Forschung, appeared in German in 1935 and that his The Open Society and Its Enemies of 1945 appeared in German in 1958. Yet Albert did much to earn this fame: his decades-long indefatigable response to criticisms of Popper's views in the post-war German philosophical literature and his constant contrast between Popper's critical rationalism and competing views that were popular in Germany at the time.