If by social practices you mean acts like your example of the one-drop rule or Joanna's of the yellow stars of david, turning over those practices would end the discrimination built on top of those symbols but it would hardly end the discrimination directed at these stigmatized groups. These people would still be marked by an array of cultural and traditional signifiers, the same ones that originally distinguished them in the minds of their community, the ones bigots wanted codified into single symbols for escalating their persecution. You'd end the convenient means of their discrimination, not the discrimination itself.
>My point is simple: prejudice and discrimination require stable categories;
thus prejudice and
I don't think that's true at all. There are several cultures that discriminate against people for being too dark in skin color when there is no clear demarcation point for what is dark and light. Say we had a society where the vast majority engaged openly in a potpourri of sexual behavior, individuals could still be discriminated for their behavior leaning toward one end of the spectrum, e.g. "too gay," "too kinky." A bigot can do just as well with clines and fuzzy boundaries as he does with discrete categories.
>You can say "X is morally irresponsible" and lecture them all you want, but
>if their world view justifies and/or requires prejudice against a group,
>your "let's all get along" strategy is a waste of time.
How exactly does considering people culpable for unjust discrimination become a "let's all get along" strategy? I don't see any naïve cheery inclusiveness in a community demanding it doesn't want members who can't accept a very basic moral premise, that it's wrong to discriminate against someone for a harmless feature of their identity. Holding people to this basic moral, rational standard has been a bedrock notion of anti-discrimination struggles for centuries, I don't see how you can so flippantly dismiss it.
Your solution certainly doesn't stand for just "getting along," it actually asks us to accommodate the world of view of bigots by blurring out the distinctiveness of the groups they want to persecute so they're unable to act on their prejudice. What kind of non-politics is this, getting society to accept diversity by making diversity imperceptible?
Arash