Engels used race ambiguously to mean both biology and social class.

Evidence

Like many other European writers in the nineteenth century, Engels tended to use the term “race” in both its biological sense, and in the sense of a class. The confusions that ensued both for Engels and his reader are evident in the passages that follow that quoted in the text: “The rough egotism of the English bourgeoisie would have kept its hold upon the working-class much more firmly if the Irish nature, generous to a fault, and ruled primarily by sentiment, had not intervened, and softened the cold, rational English character in part by a mixture of the races, and in part by the ordinary contact of life. In view of all this, it is not surprising that the working-class has gradually become a race wholly apart from the English bourgeoisie… . Thus they are two radically dissimilar nations, as unlike as difference of race could make them, of whom we on the Continent have known but one, the bourgeoisie” (ibid.). — Cedric J. Robinson, Black Marxism_ The Making of the Black…, 1595

Categorization

• DEFINE: Documents how ‘race’ as a term was deployed for class distinction in the 19th century — useful for the book’s core argument about race and the radical tradition.
• XREF: Connects to the book’s earlier treatment of how Marx and Engels’ racial vocabulary shaped their analysis of labor.