After contemplation, I think my commenters on the last post have pointed out a division between types of changes brought on by the Spirit of the Age that I had not quite thought through. They both described situations in which a person's attitudes changed gradually, in stages, however quickly. As if Year One: Women should not be allowed to use the alphabet: Year Two: Okay, Women should be able to use A, but not B or C; Year Three: okay Women can use A-D, and E and F if there are no males present, but that's it; Year Four: Women can use all letters up to P, but only lower case, etc.
What I had described is a situation in which people retained the same value, but the mode of expression completely reversed, like something a magician does when he pulls out blue flowers instead of red ones from the jar. The equivalent to the women in politics or allowing blacks into the good schools would be 1957: Blacks should make their own schools better vs 1967: We should give blacks the best schools. Or, we should not have a female president, because of gender differences to we should have only female presidents, because of gender differences.
If we could measure what is going on inside hearts and minds, as Jonathan Haidt tries to do, perhaps we would find that there is no difference between these types of change, that they are the variations of the same process. But I now suspect, as I did not quite in my original post, that these are distinct phenomenon. Keeping one's stated value unchanged, though its expression is completely inverted, is one type of sheeplike obedience to the Spirit of the Age; giving ground quickly for unclear reasons in response to social pressure is another.
Addition: Steve Sailer discusses how public perception of cops and teachers has moved recently.