 These organisations are not antipodes, they are twins.” In later years, Stalin, Grigory Zinoviev and the Communist International (Comintern) applied the term “social fascists” to the various independent Social Democratic parties, especially in Germany.Ever since the 1890s, numerous periods were under a continuing crisis of Marxist theory, including the early 1930s where German Marxist theoretician Karl Korsch warned that “Marxism today is in the midst of an historical and theoretical crisis.It is not simply a crisis within the ‘Marxist movement’, but a crisis of ‘Marxism itself.’”

Others have argued that Marxism has been in a continuous state of crisis throughout the 20th Century.