This chapter discusses the emergence of a philosophical school that is now dominant in the Anglo-American world called “analytical philosophy.” The first form taken by analytic philosophy, now long since abandoned, was logical positivism or logical empiricism (the former sympathized with phenomenalism, the latter was more realistically oriented). Logical positivism's goal is a unified science modeled on physics. The intended system of constitution seeks to move from one's own mental qualities to physical objects, from these to the mental qualities of others, and finally to the objects of the social sciences. With regard to the mental qualities of others, behaviorism, which reduces the mental to externally observable behavior, is considered a scientific conception of the world.