Karl Kautsky (1854-1938) was an Austrian and German socialist political writer and theorist.
He visited Karl Marx and Friedrich Engels in London in 1881, and after Marx's death in 1883 became close to Engels, and was chosen to edit what became the fourth volume of "Capital", "The Theories of Surplus Value".
Kautsky edited the magazine Die Neue Zeit 1883-1917, and was sometimes called the "Pope of Marxism".
In this period 1878-1890 the activities of the German Social Democratic party (SPD) were made very difficult by the German Anti-Socialist laws.
From the 1890s onwards Kautsky was an advisor to August Bebel, the leader of the SPD, and wrote an influential pamphlet justifying the party's Erfurt programme. He wrote a large number of books on socialism, and the history of socialism. He opposed the revisionism of Eduard Bernstein, with whom he had been close when they co-operated with Engels in the years between Marx's death in 1883 and Engels's death in 1895. He lost influence on the SPD leadership after the death of Bebel in 1913, and this was shown when the SPD voted for the war credits at the beginning of the First World War.
In 1917 the SPD split, and Kautsky joined the Independent Social Democratic Party (USPD), which was critical of the German government's war policy. He lost the editorship of Die Neue Zeit.
He opposed the Bolsheviks' seizure of power in 1917 and their attempts to build socialism in Russia and the Soviet Union, particularly because of their suppression of their opponents, including the other Socialist parties in Russia.
After the German Revolution of 1918 he published papers from the German diplomatic archives which showed that Kaiser Wilhelm II and the German government were largely responsible for the outbreak of the war.
In 1924 Kautsky moved to Vienna, and continued to write books on the Soviet Union and on Marxism.
When the Nazis took control of Austria in 1938, he moved to Amsterdam, where he died in October 1938.