Main article: Karl Mannheim
The German political philosophers Karl Marx (1818–1883) and Friedrich Engels (1820–1895) argued in Die Deutsche Ideologie (1846, German Ideology) and elsewhere that people's ideologies, including their social and political beliefs and opinions, are rooted in their class interests, and more broadly in the social and economic circumstances in which they live: "It is men, who in developing their material inter-course, change, along with this their real existence, their thinking and the products of their thinking. Life is not determined by consciousness, but consciousness by life" (Marx-Engels Gesamtausgabe 1/5). Under the influence of this doctrine, and of Phenomenology, the Hungarian-born German sociologist Karl Mannheim (1893–1947) gave impetus to the growth of the sociology of knowledge with his Ideologie und Utopie (1929, translated and extended in 1936 as Ideology and Utopia), although the term had been introduced five years earlier by the co-founder of the movement, the German philosopher, phenomenologist and social theorist Max Scheler (1874–1928), in Versuche zu einer Soziologie des Wissens (1924, Attempts at a Sociology of Knowledge). Mannheim feared that this interpretation could be seen to claim that all knowledge and beliefs are the products of socio-political forces since this form of relativism is self-defeating (if it is true, then it too is merely a product of socio-political forces and has no claim to truth and no persuasive force). Mannheim believed that relativism was a strange mixture of modern and ancient beliefs in that it contained within itself a belief in an absolute truth which was true for all times and places (the ancient view most often associated with Plato) and condemned other truth claims because they could not achieve this level of objectivity (an idea gleaned from Marx). Mannheim sought to escape this problem with the idea of 'relationism'. This is the idea that certain things are true only in certain times and places (a view influenced by pragmatism) however, this does not make them less true. Mannheim felt that a stratum of free-floating intellectuals (who he claimed were only loosely anchored to the class structure of society) could most perfectly realize this form of truth by creating a "dynamic synthesis" of the ideologies of other groups.