Within the Marxist movement, the word revisionism is used to refer to various ideas, principles and theories that are based on a significant revision of fundamental Marxist premises. The term is most often used by those Marxists who believe that such revisions are unwarranted and represent a "watering down" or abandonment of Marxism. As such, revisionism often carries pejorative connotations and the term has been used by many different factions. It is typically applied to others and rarely as a self-description.
The term "revisionism" has been used in a number of contexts to refer to different revisions (or claimed revisions) of Marxist theory.
In the late 19th century, revisionism was used to describe democratic socialist writers such as Eduard Bernstein and Jean Jaurès, who sought to revise Karl Marx's ideas about the transition to socialism and claimed that a revolution through force was not necessary to achieve a socialist society. The views of Bernstein and Jaurès gave rise to reformist theory, which asserts that socialism can be achieved through gradual peaceful reforms from within a capitalist system.
In the 1920s and 1930s, the International Left Opposition led by Leon Trotsky, which had been expelled from the Communist International, accused the leadership of the Comintern and Soviet Union of revising the internationalist principles of Marxism and Leninism in favor of the aspirations of an elite bureaucratic caste which had come to power in the Soviet Union. The Trotskyists saw the nascent Stalinist bureaucracy as a roadblock on the proletariat's path to world socialist revolution, and to the shifting policies of the Comintern, they counterposed the Marxist theory of Permanent Revolution. The Soviet authorities, meanwhile, labeled the Trotskyists as "revisionists" and eventually expelled them from the Communist Party of the Soviet Union, whereupon the Trotskyists founded their Fourth International.