In view of this situation, the arguments for evolution, in 1844 or 1859, were primarily significant, not as direct evidences in favor of one hypothesis, but as touchstones for deciding between the claims of two—the only two—rival hypotheses: that of the ready-made production of species, with their known characteristics and relations, by repeated special acts of creation; and that of their production through the gradual modification, in the course of natural descent, of earlier and simpler forms. Huxley, it is true, refused to face the alternative, and cried, "a plague o' both your houses V 9 Nothing can be said, however, in justification of such a position on the part of a man of science. Hypotheses non fingo has never been a sound or serviceable maxim; it had certainly not been by following it that the sciences of astronomy and geology had developed.[2] Now, if other hypotheses, beyond the two in question, were conceivable in 1844, certainly no others were seriously advanced. The first concern of a biologist of the period should, then, have been to compare the two hypotheses of the origin of species, in the light of the then known principles and facts, hereafter to be enumerated. This comparison, if made honestly, by a logically competent mind, must necessarily have led, at almost any time after 1840, to the conclusion to which Spencer tells us that he found himself forced somewhere about 1850. By this time, he says:
The belief in organic evolution had taken deep root [in my mind] and drawn to itself a large amount of evidence—evidence not derived from numerous special instances, but derived from the general aspects of organic nature and from the necessity of accepting the hypothesis of evolution when the hypothesis of special creation had been rejected. The special creation belief had dropped out of my mind many years before, and I could not remain in a suspended state; acceptance of the only possible alternative was imperative.[3]
After these preliminaries, the reader is prepared for viewing the arguments for evolutionism, now to be recalled in a more detailed manner, in their proper historical and logical perspective.
1. Argument from the General Presumption of Science against "Supernatural" Explanations of Phenomena.—In his "Belfast Address," 1874, Tyndall pointed out that the main argument for evolu-
- ↑ Chambers, "Explanations," 1846, p. 120.
- ↑ Huxley later expressed this general truth forcibly enough; e. g., "The Progress of Science," 1887. "Physical science rests on verified or uncontradicted hypotheses; and, such being the case, it is not surprising that a great condition of its progress has been the invention of verifiable hypotheses" ("Method and Results," 1902, pp. 61-62).
- ↑ "Duncan, "Life and Letters of Herbert Spencer," 1908, II., 317.
