Hegel thinks human culture finds new ideas through dialectic synthesis; in my experience, the process takes a simpler form. We aggregate everything that has worked in the recent term, then drop out whatever we’re afraid of, and push the result onto the next generation. But we stop and re-assess any time a true apocalyptic tragedy strikes.
Such an event happened in Berlin in the year 1945. The Third Reich managed to unite most of the industrial nations of the West against it and went down in flames, buried in Russian bodies and Anglo-American firepower. As the flags came down and the occupation began, history it seemed sent up a signal: nothing further in this direction, turn back now.