Full Idea
The majority of human beings do not question the truth of an idea without which they would literally be unable to live.
Gist of Idea
Most people won't question an idea's truth if they depend on it
Source
Simone Weil (Is There a Marxist Doctrine? [1943], p.163)
Book Reference
Weil,Simone: 'Oppression and Liberty' [Routledge 1955], p.163
A Reaction
I assume that this inability grows stronger with age, as the dependence on the idea runs deeper. Hence for most people the beliefs which sustain them have a higher value than truth. Obviously we should all make love of truth our guiding idea!