Based on a reconstruction of the development of Rudolf Carnap’s views from the Aufbau until the 1960s, this paper provides an account of the philosopher’s understanding of non-cognitivism, which is here seen as in line with the so-called scientific world-conception of left-wing logical empiricism. The starting point of Carnap’s conception is the claim that every human decision depends on certain attitudes that cannot be justified at a cognitive level, that are neither based on empirical facts nor logical reasoning. The key features of Carnap’s non-cognitivism, however, go beyond this general basis and involve several fundamentally moral commitments, such as a commitment toward science, and the embracing of moral attitudes as the result of a long-term process of rational discourse. I argue that these commitments contained in Carnap’s non-cognitivism/scientific world-conception establish a genuinely political worldview that is characteristic of left-wing logical empiricism and converges with socialism and democracy.