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.
Max Weber was a German historian, political economist, jurist, and sociologist. Widely regarded as one of the most influential and important theorists, Weber's ideas had a profound influence on social research and social theory. Although he did not see himself as a sociologist, Weber is often counted among the fathers of sociology alongside Émile Durkheim, Auguste Comte, and Karl Marx.