There has always been an affinity between Twardowski's students and the members of the Vienna Circle. Both are analytic philosophers in a broader sense of the term: convinced that philosophy can be done in a scientific way, they were interested in logic, and opposed to speculative metaphysics and irrationalism. Especially in the early thirties, the two groups came to know each other better. In 1930, Carnap came to Warsaw for several lectures. And in 1934, Ajdukiewicz, Łukasiewicz, Tarski and other members of the Lvov-Warsaw School went to the pre-conference of the first international congress on the unity of science in Prague, and met there Frank, Neurath, Carnap and Reichenbach. This contact was continued at the first congress in Paris, 1935, where scientific philosophy was the topic. None of the members of the Lvov-Warsaw School identified him- or herself with the Vienna Circle, for there are some important differences.