Alexander Crummell (1819–1898) was the most prominent rationalist of the black American enlightenment thinkers in the nineteenth-century. He stands out among his contemporaries—Frederick Douglass, Anna Julia Cooper, Booker T. Washington, most notably—for his robust defense of the central place of reason in moral agency. His attempts to work out the consequences of that view for the nature of language and history lends his philosophy a breadth and depth not matched by other enlightenment thinkers. The prominence of his protégé, W. E. B. Du Bois, helped ensure Crummell's continuing influence during the rise of pragmatism, but he eventually fell out of favor as such relativistic thinkers as Alain LeRoy Locke and Zora Neale Hurston emerged. . . .