Within the Marxist movement, revisionism represents various ideas, principles and theories that are based on a significant revision of fundamental Marxist premises that usually involve making an alliance with the bourgeois class. The term revisionism is most often used by those Marxists who believe that such revisions are unwarranted and represent a "watering down" or abandonment of Marxism—one such common example is the negation of class struggle. 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. By extension, people who view themselves as fighting against revisionism have often self-identified as anti-revisionists.
In the late 19th century, the term revisionism was used to describe democratic socialist writers such as Eduard Bernstein, 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 gave rise to reformist theory, which asserts that socialism can be achieved through gradual peaceful reforms from within a capitalist system.
In the 1940s and 1950s within the internationalcommunist movement, revisionism was a term used by Marxist-Leninists to describe communists who focused on consumer goods production instead of heavy industry; accepted national differences instead of promoting proletarian internationalism; and encouraged liberal reforms instead of remaining faithful to established doctrine. Revisionism was also one of the charges leveled at Titoists as punishment for their pursuit of a relatively independent communist ideology, amidst a series of post-World War II purges beginning in 1949 in Eastern Europe by the Soviet administration under Stalin. After Stalin's death, a more democratic form of socialism briefly became acceptable in Hungary during Imre Nagy's government and in Poland during Władysław Gomułka's government, containing ideas that the rest of the Soviet bloc and the Soviet Union itself variously considered revisionist, although neither Nagy nor Gomułka described themselves as revisionists, since to do so would have been self-deprecating. After the 1956 Secret Speech that denounced Stalin, many communist activists, astounded and disheartened by what they saw as the betrayal of Marxist–Leninist principles by the very people who had founded them, resigned from Western communist parties in protest. These quitters were sometimes accused of revisionism by those communists who remained in these parties, although some of these same loyalists also shortly thereafter split from the same communist parties in the 1960s to become the New Left, indicating that they too were disillusioned by the actions of the Soviet Union by that point in time. Most of those who left in the 1960s started aligning themselves with Mao Zedong as opposed to the Soviet Union. An example was E. P. Thompson's New Reasoner.