Science as a system of statements is always an object of discussion. Statements are to be compared with statements, and not with 'experience', or wit… - Otto Neurath

The members of the Vienna Circle (Moritz Schlick, Rudolf Carnap, , Hans Hahn, , Fritz Waismann, Kurt Godel, Otto Neurath and others) are working out a ‘Logical Empiricism’. Following Ernst Mach and Poincaré, but above all Russell and Wittgenstein, all the sciences are treated uniformly. Carnap’s Logischer Aufbau der Welt (1928) shows in which direction future systematic work will move. Wittgenstein’s Tractatus Logico-Philosophicus (1921) clarified, among other things, the position of logic and mathematics; besides the statements that make additions to what is meaningful, there are the ‘tautologies’ that show us which transformations are possible within language. By its syntax the language of science excludes anything that is meaningless from the very beginning.

Only one language comes into question from the start, and that is the physicalist. One can learn the physicalist language from earliest childhood. If someone makes predictions and wants to check them himself, he must count on changes in the system of his senses, he must use clocks and rulers, in short, the person supposedly in isolation already makes use of the ‘intersensual’ and ‘intersubjective’ language. The forecaster of yesterday and the controller of today are, so to speak, two persons.

At first the Vienna Circle analysed ‘physics’ in a narrower sense almost exclusively; now psychology, biology,sociology. The task of this movement is unified science and nothing less.