  It may be that Crummell thought moral criticism of this sort was appropriate, but doubted that cognitive deficit could be due to such an oppressive history. Rarely did he ascribe any black shortcoming to lingering effects of slavery, other than in the very broadest of terms. It is likely, given how much is presently understood about environmental factors in linguistic development, and how little was known then, that it didn't seem plausible to him to think there was any causal connection between slavery and cognitive resources.