Neo-Kantian philosophers sometimes divided the history of philosophy in three periods: philosophy before Kant, Kant, and philosophy after Kant. The admirers of Alfred Tarski are prone, with good justification, to propose a similar division of theories of truth. But even in our post-Tarskian period, the nature and significance of Tarski's theory of truth is still a matter of controversy.¹ Therefore, to understand better Tarski's achievement and some of our present puzzles, it is instructive to go back to the pre-Tarskian problem situation in the late 1920s and the early 1930s, and to see how Tarski's treatment of truth in Warsaw was related to alternative views current in Vienna and Berlin (Schlick, Reichenbach, Carnap, Neurath, Hempel, Popper).