To say plainly what we think of this long argumentation, we believe that it demonstrates nothing but the eminent talkative faculty of the lecturer. It all comes to this: Unmodified mammals have five fingers and five toes, whereas the modern horse has only one. Therefore the modern horse is but a modification of a pre-existing form, and is to be traced to the hipparion, the anchitherium, the orohippus, and other more ancient forms which we have not yet discovered, but which we hope to discover hereafter. Now,
this style of reasoning is simply ridiculous.
First, even granting all the premises of the professor, the conclusion that one species is derived from another by evolution would still remain unproved. For who told Prof. Huxley that the animal remains on which he bases his argument belong to different species, and not to different varieties of one and the same species? Surely, a greater or less development of one or two bones cannot be considered a sufficient evidence of specific difference; for we know that even in the same variety there may be a different development; as in the hound, which sometimes possesses a spurious hind toe, and in the mastiff, which occasionally shows the same peculiarity. Hence the professor has no right to assume that the horse, the hipparion, the anchitherium, etc., are animals of different species; and therefore his argument has nothing to do with the evolution of one species from another.
Secondly, to assume without proof that “unmodified mammalia” have five fingers and five toes is to assume without proof the very conclusion which was to be demonstrated; for it is to assume that the modern horse, which has neither five fingers nor five toes, is not an unmodified mammal, but a product evolved by some more ancient form. Now, this is what logicians call petitio principii.
Thirdly, what does Prof. Huxley mean by unmodified mammalia? What are they? For, in his theory of evolution, every animal is a modification of a preceding form, and the whole series of living beings contains nothing but modified organisms. To find, therefore, an unmodified mammal, it would be
necessary to find the first of all mammals from which all other mammals of the same class have proceeded. This first mammal is still to be discovered, as the professor concedes. How, then, could he know that the unmodified mammal has five fingers and five toes? And if he did not know this, how did he assume it as the very ground of his pretended demonstration?
Fourthly, how does Prof. Huxley know that the horse proceeds from the hipparion, the hipparion from the anchitherium, and the anchitherium from the orohippus? Of this he knows nothing whatever. He has no other ground for his assertion, except the different ages to which those deposits belong: but a difference of age does not prove that the older is the parent of the younger. Alexander the Great existed before Annibal, Annibal before Cæsar, Cæsar before Napoleon. Will our professor infer from this that Napoleon was the lineal descendant of Alexander the Great?
Fifthly, it is not true that “the history corresponds exactly with what one could construct a priori from the principles of evolution.” The principles of the theory of evolution demand that the more complex organisms be considered as evolved from the less complex, and the more developed as evolved from the less developed; for, according to the theory, the further we go back towards the origin of life, the nearer we approach the “protoplasm” or the “gelatinous matter.” It would therefore be more in accordance with the theory of evolution to say that the five-toed animals must have proceeded from animals possessing a simpler and less developed organism, and that the horse is the parent of the
hipparion, and of the anchitherium and of the orohippus, which is quite contrary to geological evidence. Hence geological evidence flatly contradicts the principles of evolution. In other terms, if mammalia of different species have been evolved from one another, those animals whose organism is more developed must be more modern. Now, the orohippus has an organism more developed than that of the horse. Therefore the orohippus, by the principles of the theory, is more modern than the existing horse. But geological evidence shows the contrary. Therefore geological evidence directly conflicts with the principles of evolution.
Sixthly, the whole argument of the professor may be condensed in the following syllogism: If the theory of evolution is true, then we must find such and such fossils. But we find such and such fossils. Therefore the theory of evolution is true. By this form of reasoning one would prove anything he likes. Thus, for example, we might say, if Professor Huxley has graduated at Yale College, New Haven, he must know the English language. But he knows the English language. Therefore he has graduated at Yale College, New Haven. The fallacy consists in supposing that such and such fossils could not be found, except in the hypothesis that evolution is true. Hence, to avoid the fallacy, the conditionate proposition should have been inverted—that is, it should have been: If we find such and such fossils in such and such deposits, then the theory of evolution is true. But this proposition could not be assumed without proofs.