Or if, as in the above instance of the Argus' eyes, a series is actually found, it is even less difficult to take for granted that it can have but one significance; while such assumptions are too frequently[{178}] accepted without hesitation or demur, although it would be no easy task to show that they rest upon any solid grounds. When, in addition, either Mr. Darwin himself or some of his leading partisans has declared that some unverified process has undoubtedly occurred, or that they see no reason to doubt its occurrence, or that nothing which we know precludes its possibility,—it appears to be widely supposed that something substantial is thereby added to the scientific evidence, and that the suppositions thus sanctioned may even rank as facts. But however such a method may avail to secure acceptance for a doctrine, it does nothing for its scientific value. Such a style, as Mr. Mivart says,[204] is calculated to impress only minds too easily dominated, and not prepared by special studies accurately to weigh the evidence put before them.
Illustrations of this strange method of procedure are furnished in connexion with various points already mentioned. Thus, as we have seen, Mr. Darwin attempts to explain the origin of rational speech, by the conscious utterance of a significant sound by an unusually wise ape-like creature. In favour of this very large suggestion, Mr. Darwin has nothing more substantial to say[205] than that "it does not appear altogether incredible," which does not appear to take us very far.[206] Yet I have[{179}] seen this described as an "idyllic scene" shedding an entirely new light on the subject. So again in regard of the evolution of the eye.[207] Having summarily enumerated the various stages of development exhibited by this organ as actually existing in various animals, Mr. Darwin goes on to say that when we remember how small the number of living forms must be in comparison with extinct, and the other gradations that may consequently have existed, "the difficulty ceases to be very great" in believing that Natural Selection has connected the most rudimentary with the perfect structure. Similarly, as to the cell-making instinct of the bee,[208] having postulated four several suppositions for which evidence is not forthcoming, he concludes: "By such modification of instincts ... I believe that the hive bee has acquired, through natural selection, her inimitable architectural powers."[209] Similar examples might be multiplied indefinitely.
Not unfrequently the tone of such utterances is more imperious. Thus, of the descent of Man from some animal ancestor Mr. Darwin pronounces[210] "The grounds upon which this conclusion rests will never be shaken," and again[211] "the possession of[{180}] exalted mental powers is no insuperable objection to this conclusion" ... "It is only [p. 32] our natural prejudice which leads us to demur to this conclusion." He even goes so far as to declare that his view is forced upon every man who is not content to assume the mental attitude of a savage.[212]
Argumentation of this character, which he finds common with Darwin to other Evolutionists, is judged by de Quatrefages to be one of the weakest and most misleading features of their systems.
Personal conviction [he writes],[213] mere possibility, are offered as proofs, or at least as arguments in favour of the theory. Can we admit their validity? Obviously not. The human mind can conceive many things: is that a reason for accepting them all?... Obviously more serious proofs are needed. After all, save where a contradiction is involved, everything is possible.... If adopting, under the shadow of Oken's great name, his principle of the repetition of phenomena, a naturalist should maintain that each of the planets has its own Europe, its England, and its Darwin expounding to the Jovians and Saturnians the origin of species, I do not quite see how one would set about showing him that he was wrong. Unquestionably the thing is possible. Are we to draw the conclusion that it is a fact?
Again,[214] the same distinguished naturalist, having quoted Darwin's very elaborate explanation of a difficulty, remarks:[{181}]
We see how with Darwin, as with his precursors, one hypothesis necessitates another. But can he, at least, by means of these subsidiary theories, these comparisons, these metaphors, account for all the facts? No, he himself honestly confesses more than once that he cannot. It is true that he adds "I am convinced that the objections have little weight, and the difficulties are not insoluble." But is this conviction of his a proof, or even an argument?
M. Blanchard likewise comments vigorously on this mode of argumentation. Speaking of the Mole and Darwin's explanation of its blindness, namely that having taken to living under-ground it lost its eyes through disuse—which he considers a most preposterous supposition,—M Blanchard continues:[215]
The realms of fancy are boundless; but the observer who is concerned with realities can only have recourse to the facts of science. Fossil remains discovered in very ancient strata show that the underground animal of present times does not differ from his geological counterpart. The Mole belongs to a very peculiar type, and has no nearer European relatives than the Hedgehog and the Shrew. Can we imagine a common ancestor of Shrews, Hedgehogs, and Moles? On this point Mr. Darwin expresses no opinion,—which should not be, for when confronted by forms clearly differentiated, he is wont to extricate himself from difficulties with matchless facility. The intermediate links, he will say, were doubtless[{182}] less fitted to live than were the others, and so have disappeared. After that the Evolutionists consider any one quite out of date who does not consider himself entirely satisfied with so felicitous an explanation.
M. de Quatrefages denounces another fatal defect often observable in the method of proof.