Philosophy of science emerged as a distinctive part of philosophy in the twentieth century. Its birthplace was continental Europe, where the neat Kantian scheme of synthetic a priori principles that were supposed to be necessary for the very possibility of experience (and of science, in general) clashed with the revolutionary changes within the sciences and mathematics at the turn of the twentieth century. The systematic study of the metaphysical and epistemological foundations of science acquired great urgency and found its formative moment in the philosophical work of a group of radical and innovative thinkers – the logical positivists – that gathered around Moritz Schlick in Vienna in the 1920s.