There are, no doubt, evolutionists who mingle enough dualism with their philosophy to mitigate the most objectionable aspects of its basic monism. In so doing, however, they are governed by considerations that are wholly extraneous to evolutionary thought. Indeed, if we take Kellogg’s words at their face value (that is, in a sense which he would probably disclaim), it is in spite of his philosophy that the evolutionist is a spiritualist. “And just as religion and cheating,” reasons Kellogg, “can apparently be compassed in one man, so can one man be both evolutionist and idealist.” (_Loc. cit._, p. 490.) If this comparison holds true, the evolutionist can be an idealist only to the extent that he is inconsistent or hypocritical, since under no other supposition could piety and crime coëxist in one and the same person. Be that as it may, the majority of evolutionists are avowed mechanists and materialists, in all that concerns the explanation of natural phenomena. “That there may be God who has put his Spirit into men” (Kellogg, _ibid._, p. 491), they are condescendingly willing to concede. And small credit to them for this; for who can _disprove_ the existence of God, or the spirituality of the human soul? Nevertheless, it is impossible, they maintain, to be _certain_ on these subjects. Natural science is in their eyes the only form of human knowledge that has any objective validity. Proofs of human spirituality they denounce as _metaphysical_, and metaphysics is for them synonymous with “such stuff as dreams are made of,” unworthy to be mentioned in the same breath with physical science—“Es gibt für uns kein anderes Erkennen als das mechanische, ... Nur mechanisch begreifen ist Wissenschaft.” (Du Bois-Reymond.)