Karl Kautsky (1854–1938) was a major figure in the history of Marxism in the years following the deaths of both Marx and Engels.. Here are some of his major contributions: 1. Orthodox Marxism and Popularizing Marxist Theory  Kautsky played a pivotal role in the development of Orthodox Marxism, which emphasized a strict adherence to Marx and Engels' works. He was known for translating Marxist theory into a more accessible form, which helped popularize Marxist ideas among workers and intellectuals. He achieved status as a prominent Marxist theorist in 1888, when Frederick Engels assigned him to editing Marx's three- volume work Theories of Surplus Value. This was compiled from notes that Marx had left behind for what had been projected to be the fourth volume of Capital.  His work "The Economic Doctrines of Karl Marx" (1887) is one of the earliest summaries of Marx's economic theory, making Marxist ideas more comprehensible to a broader audience. During his own time Kautsky was often referred to by both admirers and critics as the "pope of Marxism."  His interpretations of Marxism tended to emphasize its scientific, materialist, and determinist character. Before becoming a Marxist, Kautsky had achieved some notoriety as a popularizer and defender of Darwinism. After he became a Marxist he was inclined to perceive affinities between the two and that helped to shape the ways that he interpreted Marxism. 2. Role in the Second International  Kautsky was a key figure in the Second International (1889–1916), a global socialist organization aimed at coordinating efforts of socialist parties across countries. He became one of its leading theorists and advocated for international socialism through parliamentary democracy rather than violent revolution, a stance that contrasted with later revolutionary Marxists, and which would eventually put him at loggerheads with people like Lenin, Rosa Luxemburg, and Karl Liebknecht.. 3. Theory of Evolutionary Socialism  Kautsky promoted the idea that socialism would evolve gradually through democratic means, rather than through an immediate and violent proletarian revolution. He argued that capitalism’s internal contradictions would inevitably lead to its collapse and the rise of socialism. I think he had some responsibility for the notion, that was widespread in the Second International, that the triumph of socialism was inevitable.  This theory of "evolutionary socialism" differed from the more radical views of Marxists like Rosa Luxemburg and Vladimir Lenin, who believed that revolution was necessary to overthrow capitalism. 4. Criticism of Revisionism