[1] Kautsky's views of Marxism dominated the European Marxist movement for two decades, and orthodox Marxism was the official philosophy of the majority of the socialist movement as represented in the Second International until the First World War in 1914, whose outbreak caused Kautsky's influence to wane and brought to prominence the orthodoxy of Vladimir Lenin.
Orthodox Marxism maintained that Marx's historical materialism was a science which revealed the laws of history and proved that the collapse of capitalism and its replacement by socialism were inevitable.
[2] For example, this idea saw the Social Democratic Party of Germany (SPD) adopt a gradualist approach, taking advantage of bourgeois parliamentary democracy to improve the lives of workers until capitalism was brought down by its objective internal contradictions.
[7] In contrast, the anti-revisionist tradition criticised official Communist parties from the opposite perspective as having abandoned the orthodox Marxism of the founders.
[11][9] Impossibilism also opposes the idea of a vanguard-led revolution and the centralization of political power in any elite group of people as espoused by Leninism and Marxism–Leninism.
This perspective is maintained by the World Socialist Movement, De Leonism, and to some extent followers of Karl Kautsky and pre-reformist social democracy.
The official thought of the Third International was based in orthodox Marxism combined with Leninist views on revolutionary organization initially.
Luxemburgism is also highly critical of the reformist Marxism that emerged from the work of Eduard Bernstein's informal faction of the Social Democratic Party of Germany.
[19][20] Though the periods and countries defined as state capitalist or revisionist varies among different ideologies and parties, all of them accept that the Soviet Union was socialist during Stalin's time.
[21] Menshevism refers to the political positions taken by the Menshevik faction of the Russian Social Democratic Labour Party prior to the October Revolution of 1917.
Kautsky was an outspoken critic of Bolshevism and Leninism, seeing the Bolsheviks (or Communists as they had renamed themselves after 1917) as an organization that had gained power by a coup and initiated revolutionary changes for which there was no economic rationale in Russia.
It is the scientific conviction that dialectical materialism is the road to truth and that its methods can be developed, expanded and deepened only along the lines laid down by its founders.
Beyond accumulating knowledge relevant to an orthodox Marxist line, they felt the need to take the more critical and negative approach that is required for the maintenance of an integral and penetrating understanding of society during a moment of reaction.
In the postwar period, the New Left and new social movements gave rise to intellectual and political currents which again challenged orthodox Marxism.