A sequence of theoretical models is constructed as an extension to Leszek Nowak's theory of socialist society to explain important characteristics of the violent party purges in Soviet Stalinism. According to these models, purges are a regular and systemic feature of a socialist system during a certain phase of development (modelled as the ‘phase of social enslavement’). Contrary to traditional conceptions which interpret the purges essentially as resulting from the actions of an almost omnipotent, and partly irrational, despot, the models presented here provide an explanation which does not need to conceive Stalin as the “architect of terror” (Robert Conquest), i.e. as the long-term planner of the terror. However, the concepts presented here preserve the vital arguments of the traditional approach, thereby contradicting the ‘revisionist’ pattern of interpretation. In particular the models seek to provide a theoretical base for an explanation of the moderation of inner-party terror from 1938. This moderation is interpreted as resulting from a modification of the then existing ideology (and corresponding habits of the party's leadership); a modification which in itself had been stimulated by the disastrous effects of the ‘great purge’ in 1937/38. This modification can be theoretically conceived as a process of ‘ideological learning’. The historical fact that the post-war purges (i.e. the ‘Leningrad affair’ in 1949 and the ‘Mingrelian affair’ 1951/52) did not reach such an enormous extent as the purges of the late 1930s may thus be attributed to a process of ‘ideological learning’.