I've discovered the need to adopt a new way of speaking about people who are recently-descended from Africans. We've learned in the last couple decades that we ought to emphasize someone's personhood above any other characteristic, and thus it's thoroughly immoral to use any adjective in front of 'person'. We need to use predicate nouns instead. We no longer have sad people, for example. We simply have people with sadness. We no longer have short people. We have people with shortness. We don't want to define people with sadness as if their sadness is more important than their personhood, so we have a moral obligation to put the noun form after the word 'person'. Grammar does always indicate metaphysics, after all.
One sphere of language in which this lesson has never been properly applied is in the area of race. Why are we still talking about black people, for instance? Do we really want to define people solely in terms of their race? Do we really want to signal that their blackness is so central to who they are that we're going to pretend that people with blackness aren't people? If we call them black people, then we are treating their blackness as if it's a greater part of our conception of people with blackness than their personhood is. People with person-firstness have instructed us that we should never put disability-related adjectives in front of a noun or pronoun referring to a person, because we don't want them identified with that condition. But we've also learned from the same people that having a disability is not negative, which means this policy is not because disabilities are bad. Therefore, we ought to apply it to other cases when something is not bad but might wrongly be taken by someone to be bad, just as we would apply it to things that are genuinely bad. If race is not to be a negative, then I am not a white person. I'm a person with whiteness. It does make it a little awkward to speak of people with Asianness or people with Australian-first-people-ness (i.e. what used to be called aboriginalness). But it's worth the awkwardness of expression to avoid any chance of identifying them with the racial or ethnic group whose membership they possess.
Even worse, it's especially pernicious to say that someone is black (or African-American or whatever racial term we might choose). After all, using predicate adjectives amounts to making identity statements rather than merely ascribing a property to someone the way we would have thought that adjectives in English, even predicate adjectives, do. It's much more preferable to say that someone has blackness than to say that she is black. People aren't anything except persons. I'm not philosophical. I have philosophicalness. Glenn Beck is not unfair to his political adversaries. He has unfairness to the people who have political adversariness with him. President Obama is not bad at speaking without a teleprompter. He has badness at speaking without a teleprompter. I shouldn't say that I am Christian. I'm a person who has Christianity. I shouldn't be identified with my faith. I should claim, rather, to possess the entirety of Christianity, as if it belongs to me. We need to avoid identifying people with any property ascribed to them other than personhood. It's much better to say that they possess the entirety of the thing that formerly we would have used to describe them.
For more explanation, please see here (except you can ignore the sections explaining how people with blindness and people with deafness have offendedness at the obviously-correct way to refer to them, and you certainly shouldn't read person-with-autism Jim Sinclair's reasons for disliking person-first language).