Bourdieu's engine concept: the set of durable dispositions a social position installs in a body, posture, accent, appetite, timing, the sense of what is for us and what is not for us, which then generates the behaviors that reproduce the position.
Documented
The concept
Documented: Bourdieu's habitus, systems of durable, transposable dispositions, structured structures predisposed to function as structuring structures, runs from Outline of a Theory of Practice (1972) through Distinction and The Logic of Practice (1980). It operates below deliberation: the sense of the game, what feels natural, possible, ridiculous, or out of reach, for people from your position.
Assessment: Documented: the definitions across the texts. The concept's opacity is famous and the definitions are quoted verbatim in the scholarship.
Stories
The old word
The documented genealogy: habitus is ancient, Aristotle's hexis translated into Latin, Aquinas's term for acquired virtue, Panofsky's art-historical usage, which Bourdieu credited. Bourdieu's innovation was not the word but the sociology: dispositions indexed to class position, measurable in survey data, reproducing structure without anyone commanding it.
Assessment: Documented: the hexis-to-habitus lineage is in the literature, with Bourdieu's own acknowledgment of Panofsky. A Thomistic word became sociology's load-bearing concept.
Interesting claims
The hysteresis
The documented edge case that makes the concept falsifiable: hysteresis, the lag when the field changes faster than the habitus, producing bodies calibrated to a world that no longer exists, the peasant in the boardroom, the pensioned worker in the gig economy. The lag, not the fit, is where the theory shows its mechanism.
Assessment: Interesting: hysteresis is in Bourdieu's own texts. The theory predicts its own failure modes, which is more than most social theory manages.
Sources and further reading
Bourdieu, Outline of a Theory of Practice, 1972; The Logic of Practice, 1980 (primary definitions)
Aristotle's hexis to Aquinas's habitus lineage; Bourdieu's acknowledgment of Erwin Panofsky (documented genealogy)
The hysteresis discussions in Bourdieu's later texts (the concept's own edge case)
Worth asking
If your instincts are your biography, which instincts were installed, and by which address?