The foregoing makes it patent that Nietzsche was a thorough-going and uncompromising biological monist. That is to say, he believed that man, while superior to all other animals because of his greater development, was, after all, merely an animal, like the rest of them; that the struggle for existence went on among human beings exactly as it went on among the lions in the jungle and the protozoa in the sea ooze, and that the law of natural selection ruled all of animated nature--mind and matter--alike. Indeed, it is but just to credit him with being the pioneer among modern monists of this school, for he stated and defended the doctrine of morphological universality at a time when practically all the evolutionists doubted it, and had pretty well proved its truth some years before Haeckel wrote his "Monism" and "The Riddle of the Universe."
criticism · Christianity
Nietzsche as a biological monist
Mencken argues that Nietzsche was a thorough-going biological monist who held man to be merely an animal under the law of natural selection, and credits him as a pioneer of this view before Haeckel.