The main theme of these lectures is man's struggle to understand himself as a social being. The author argues that the chief inspiration for this effort, insofar as it has been successful, has been the rationalist philosophy of physical science, and that constructive social science has been based on this philosophy rather than upon theology and ethical philosophy. He goes on to discuss the major problems confronting man in his attempts to come to grips with the modern social world - problems of social and political organization, of equality and aspiration, of intellect and reason - and ends with a plea for liberalism and rationalism as the political and intellectual foundations of freedom and progress. This fascinating and thought-provoking apology for liberalism and the social scientist will be valuable reading for anyone interested in problems facing them both today.