At the very end of Skepticism and Freedom, Richard Epstein observes:
What is so difficult to fathom is how political knowledge ebbs and flows while scientific and technical knowledge is able to grow and progress in continuous, if not wholly orderly, fashion.
This is indeed a puzzle, and one worth spending considerable time pondering because of its central importance to humanity.
Via the BackReaction blog, today we have a partial answer from a computer scientist: click here for link to pdf. One implication seems to be that cultural norms, to stay durable, probably require their underlying reasons or theories to be re-articulated by each new generation. That's because when we don't re-articulate, we forget.
Actually, this principle seems to be deeply embedded in certain religious traditions (such as liturgies). Religious doctrine, like other cultural norms, can become disconnected from original motivating reasons for the doctrine as collective memory fades into empty repetition.