At the end of his General Theory of Employment, Interest and Money John Maynard Keynes (1954: 383) wrote ‘Practical men who believe themselves to be quite exempt from any intellectual influences, are usually the slaves of some defunct economist. Madmen in authority, who hear voices in the air, are distilling their frenzy from some academic scribbler of a few years back.’

Keynes is recognising the role ideas play in culture. Since the end of the 19th century this has taken the form of a discussion about ideology. Karl Marx in particular wanted to insist on the dialectic between ideas and modes of production. In the German Ideology he noted that morality, religion, and so forth,

In the third of his theses on Feuerbach Marx puts this more dialectically, reminding materialists inclined to read off the human condition simply from circumstances and upbringing that it is ‘human beings who change circumstances’ (Marx and Engels, 1976: 3). Just to spell this out: theologies, like all other forms of discourse, change as modes of production and material intercourse change, but equally human beings, believing thus and thus, celebrating the eucharist thus and not otherwise, change circumstances.

As an example of how religious ideologies bear on human circumstances E.P. Thompson (1968) (following Marx) cited Andrew Ure's Philosophy of Manufactures (1835/1967), to show how Christianity was used in industrial capitalism. Ure argues that religion is necessary to create a well-disciplined work force. Some power is needed to turn recalcitrant workers into docile wage slaves: