[1] Karl Mannheim was born 27 March 1893 in Budapest, to a Hungarian father, a textile merchant, and German mother, both of Jewish descent.

[3] In the brief period of the Hungarian Soviet Republic, in 1919, Mannheim taught in the Pedagogical Institute of the University of Budapest thanks to the patronage of his friend and mentor Lukács,[4] whose political conversion to communism he did not share.

[7] In 1926, Mannheim had his habilitation accepted by the faculty of social sciences, thus satisfying the requirements to teach classes in sociology at Heidelberg.

Greta Kuckhoff, who later became a prominent figure in the DDR, was his administrative assistant in Frankfurt, leaving early in 1933 to study at the London School of Economics (LSE) and prepare for Mannheim's emigration there.

[10] After fleeing the Nazi regime and settling in Britain, Mannheim became a lecturer in sociology at the London School of Economics, under a program to assist academic exiles.

In his work, he sought variously to synthesize elements derived from German historicism, Marxism, phenomenology, sociology, and Anglo-American pragmatism.

In the autumn of 1915, he was the youngest founding member[13] of the Sonntagskreis (Sunday Circle) alongside Béla Balázs, Lajos Fülep, and György Lukács, where a wide range of literary and philosophical topics were discussed.

Mannheim's Hungarian writings, notably his doctoral dissertation "Structural Analysis of Epistemology,"[5] anticipate his lifelong search for "synthesis" between these currents.

[5] Yet they did not exclude Marxist themes and Mannheim's work was influenced by Lukács' later turn to Marxism, for example he credits Marx as a key source of the sociology of knowledge.

[5] Sociologist Brian Longhurst explains that his work on epistemology represents the height of his early "idealist" phase, and transition to hermeneutic "issues of interpretation within culture".

Arguments between Mannheim and Horkheimer played out in faculty forums, like the Kant Gesellschaft and Paul Tillich's Christian Socialist discussion group.

While the conflict between Mannheim, Adorno and Horkheimer looms large in retrospect, Mannheim's most active contemporary competitors were in fact other academic sociologists, notably the proto-fascist Leipzig professor, Hans Freyer, and the proponent of formal sociology and leading figure in the profession at the time, Leopold von Wiese.

[18] Mannheim claimed that the sociology of knowledge has to be understood as the visionary expression of "historical experience which has social reality at its vital center.

In his British phase Mannheim attempted a comprehensive analysis of the structure of modern society by way of democratic social planning and education.

[5] In Diagnosis of Our Time, Mannheim expands on this argument and expresses concern for the transition from liberal order to planned democracy, according to Longhurst, arguing "...the embryonic planned democratic society can develop along democratic or dictatorial routes...as expressed in the totalitarian societies of Nazi Germany and the Soviet Union".

His books on planning nevertheless played an important part in the political debates of the immediate post-war years, both in the United States and in several European countries.

Mannheim's sociological theorizing has been the subject of numerous book-length studies, evidence of an international interest in his principal themes.