Karl Mannheim's major contribution was in sociology of knowledge which was defined as a theory of existential or social conditioning of thought. He considered that ideological knowledge is often placed within the given social structure and historical process hence such knowledge is situationally relative. The social structure to which ideas are bound are seen mainly in terms of class factors or status groups.
In his book 'Ideology and Utopia' he considers that ideological knowledge or thought is propounded by those benefitting from status quo whereas utopia is rooted in the thoughts of under privileged. Mannheim also stressed on the generational element in his thought,just like social class,one's generation also determines thought. Due to the ideological characteristics of thought he was accused of adopting a position of total relativism. However his central ideas and contribution to sociology was substatntive and not epistemological.