School of philosophy risen in Austria and Germany during 1920s, primarily concerned with the logical analysis of scientific knowledge. Among its members were Moritz Schlick, founder of the Vienna Circle, Rudolf Carnap, the leading figure of logical positivism, Hans Reichenbach, founder of the Berlin Circle, Herbert Feigl, Philipp Frank, Kurt Grelling, Hans Hahn, Carl Gustav Hempel, Victor Kraft, Otto Neurath, Friedrich Waismann. During 1930s the most important representatives of logical positivism emigrated to USA, where they influenced American philosophy.
Logical knowledge includes mathematics, which is reducible to formal logic.
Empirical knowledge includes physics, biology, psychology, etc. If they were, with respect to time, at the beginning of the knowledge, then they would be logically useless. Obviously if and only if we are able to exactly describe the conditions in which it is possible to answer yes, or, respectively, the conditions in which it is necessary to answer with a no. The definition of the circumstances under which a statement is true is perfectly equivalent to the definition of its meaning. The only role of philosophy is the clarification of the meaning of statements and their logical interrelationships.