“The unpardonable forgetfulness in which the lower animals have hitherto been left by the moralists of Europe is well known. It is pretended that the beasts have no rights. They persuade themselves that our conduct in regard to them has nothing to do with morals, or (to speak the language of their morality) that we have no duties towards animals : a doctrine revolting, gross, and barbarous, peculiar to the west, and having its root in Judaism. In philosophy, however, it is made to rest upon a hypothesis, admitted, in despite of evidence itself, of an absolute difference between man and beast. It is Descartes who has proclaimed it in the clearest and most decisive manner; and in fact it was a necessary consequence of his errors. The Cartesian - Leibnitzian - Wolfian philosophy, with the assistance of entirely abstract notions, had built up the ‘rational psychology,’ and constructed an immortal anima rationalis: but, visibly, the world of beasts, with its very natural claims, stood up against this exclusive monopoly—this brevet of immortality decreed to man alone—and silently Nature did what she always does in such cases—she protested. Our philosophers, feeling their scientific conscience quite disturbed, were forced to attempt to consolidate their ‘ rational psychology ‘ by the aid of empiricism. They therefore set themselves to work to hollow out between man and beast an enormous abyss, of an immeasurable width; by this they wish to prove to us, in contempt of evidence, an impassable difference.”

                            – Schopenhauer’s ” Foundation of Morality.”

Here, Schopenhauer finds fault in the premised ontological dualism between human and nonhuman animals. “In contempt of the evidence” we operate on the assumption, partially grounded, I believe, in baseless Judeo-Christian premises, that the gulf between “us” and “them” is so great as to make ethical considerations irrelevant. 

From this assumption, we are guided by rhetorical tools as opposed to reason. For example, the word human is used to mean “not animal” or “better than animal” when in actuality human beings are a species of mammal. As Jen recently remarked, imprecise language of this kind is a means to an end. And that end is the oppression of some group.