  One could read Crummell's various arguments about posterity and moral change (below), as well as his case for black civil rights (above), as a vindication of this idea. He may be interpreted as making a moral case for black progress and civilization precisely as a moral offset to the moral harm that has plagued blacks. But the sticking point in that interpretation would be his understanding of language and cognition. If his goal is to provide a moral counterweight to discrimination and its effects, it seems he hasn't pursued it through all of its effects—specifically those that concern cognition and linguistic ability. He is quite unsparing in his analysis of civil rights; why wouldn't he also articulate his case in terms of language and reasoning, if that was his real purpose? And the complaint implicit in the question stands as a criticism.