The second part of Herder's Ideas for a Philosophy of the History of Mankind (1785) contains a chapter with the heading: “In all the different forms in which the human race (Menschengeschlecht) appears on earth, it is nonetheless everywhere one and the same human species” (Menschengattung) (Ideas, 251). In this chapter of the Ideas, Herder takes issue with the concept of race being developed by some of his contemporaries. The special target of his remarks is again Kant, whose “On the Different Races of Man” (Von den verschiedenen Racen der Menschen), appearing in 1775, had divided the human species into four fixed and sharply distinct races. Against such accounts, Herder says:

Herder's polemical remarks on the concept of race in the Ideas have a practical, as well as an epistemological, intent. The debate about race has significant ethical and political implications, and Herder's position within this debate is meant to support his admonition, directed towards his fellow Europeans, that, unlike the higher apes, “the American and the Negro” are your brothers, and that “therefore, you must not oppress or kill or rob them: for they are human beings, as you are” (Ideas, 255).