Karl Mannheim was one of the most influential sociologists of the early 20th century. He received a doctorate in philosophy from the University of Budapest, but soon immigrated to Germany in response to Hungary’s political turmoil. There he studied with Alfred Weber (brother of Max) and published his most influential work, Ideology and Utopia (1929) – one of the founding texts of the sociology of knowledge. For Mannheim, as for Marx and other early sociologists, our knowledge is historically constructed. Mannheim, though, argues that this construction can take different forms, with different political outcomes.