Karl Marx, the philosopher, economist, political theorist and socialist revolutionary, is best-known for the 1848 pamphlet, The Communist Manifesto and the three-volume Das Kapital. His theories, called Marxism, maintained that class conflict leads to the development of human societies and that internal tension were inherent in capitalism, which would ultimately be replaced by the socialist mode of production.
German-born American political scientist and historian Hans Morgenthau, a leading twentieth-century figure in the study of international relations, is noted for his contributions in international relations theory and the study of international law. His book Politics Among Nations introduced the concept of political realism that played an instrumental role in the foreign policy of the US.
Ralf Dahrendorf was a German-British sociologist, philosopher, and political scientist. As a class conflict theorist, he was a leading expert on analyzing class divisions in modern society. He was the author of multiple articles and books, including Class Conflict in Industrial Society (1959). He served as a professor of sociology in several universities in Germany and the UK.
Friedrich Ratzel was a German ethnographer and geographer. He was the first person to use the term Lebensraum, which would later become an important and popular word among the National Socialists. Also an influential writer, Friedrich Ratzel's works served as a justification for imperial expansion.
Hamed Abdel-Samad is a German-Egyptian author and political scientist. A member of the Society of the Muslim Brothers during his university days, Hamed Abdel-Samad later questioned his own beliefs and published a controversial book titled My Farewell from Heaven, which he said was neither a call to renounce the Muslim faith nor an attack on his culture.