But in this preliminary chapter I ought to state what I understand to be the scientific hypothesis or hypotheses with which I propose to contrast the idea of God as the creator of species by applying the test of probability. To discuss the superior claims of one hypothesis over another, without showing that there is a real conflict between them, would be to set up a man of straw for the sake of knocking it down as if it were a living and real antagonist. What I desire to do is not to aim at a cheap victory by attacking something that does not call for opposition; but it is to ascertain first whether there is now current any explanation or hypothesis concerning the origin of the creation, or anything that it contains, which rejects the idea of God as the creator of that which we know to exist and as it exists, and then to ascertain which of the two hypotheses ought to be accepted as the truth, because it has in its favor the highest attainable amount of probability. There is an amount of probability which becomes to us a moral demonstration, because our minds are so constituted that conviction depends upon the completeness with which the evidence in favor of one hypothesis excludes the other from the category of rational beliefs. I pass by the common sort of infidelity which rejects the idea of an intelligent creator acting in any manner whatever, whether by special creations or by laws of development operating on some primordial form of animal life. But among the modern scientists who have propounded explanations of the origin of species, I distinguish those who do not, as I understand, deny that there was an intelligent Creator by whose will some form of animal life was originally called into being, but who maintain that the diversified forms of animal life which we now see were not brought into being by the special will of the Creator as we now know them, but that they were evolved, by a process called natural selection, out of some lower type of animated organism. Of this class, the late Mr. Darwin is a representative. There is, however, at least one philosopher who carries the doctrine of evolution much farther, and who, if I rightly understand him, rejects any act of creation, even of the lowest and simplest type of animal existence. This is Mr. Herbert Spencer--a writer who, while he concurs in Mr. Darwin's general theory of natural selection as the process by which distinct organisms have been evolved out of other organisms, does not admit of any primal organism as the origin of the whole series of animals and as the creation of an intelligent will.