The American political tradition that began in domestic policy as a disillusionment with liberal social engineering and ended, three decades later, as the most assertive foreign-policy school in postwar Washington. Irving Kristol's definition — a liberal who has been mugged by reality — captures the trajectory better than any doctrine, because neoconservatism was a migration before it was a position.
Its founders were largely anti-Stalinist New York intellectuals of the 1930s and 1940s, who had learned to argue against communism from inside the left. The Public Interest, founded by Kristol and Daniel Bell in 1965, made the domestic case: not that the Great Society's aims were wrong, but that its programmes produced unintended consequences its designers had not modelled, and that social science ought to be used to check enthusiasm rather than fuel it. Leo Strauss's influence on the movement is real but routinely overstated, and the claim that his esoteric teaching secretly directed policy has served mostly as a conspiracy theory.
The foreign-policy turn came through the Cold War. Jeane Kirkpatrick's Dictatorships and Double Standards (1979) argued that authoritarian allies were reformable while totalitarian regimes were not, supplying a rationale for supporting the former. After 1989 the tradition moved from containment to promotion — the conviction that liberal democracy is universally applicable and that American power should actively spread it, which culminated in the Iraq war of 2003.
That war largely discredited the tradition, and its own adherents divide over whether the failure was in the theory or the execution. The label has also been put to uses worth naming plainly: applied to a group of substantially Jewish intellectuals, it has often functioned as an antisemitic euphemism for a supposed foreign influence on American policy, which is a reason to use the word precisely rather than to avoid it.