“The proof is in the pudding” if we’re sticking with idioms. Where the evidence of systemic racism is a lack of wealth, discriminate on wealth. Where the evidence is family structure, discriminate on family structure. Address disadvantage by addressing disadvantage, not by a racial proxy.

In programmer terms, racial affirmative action is a very lossy hash of reality, which leaves a lot of room for injustice both in terms of who it helps and who it doesn’t.