THE ARGUMENT FOR ORGANIC EVOLUTION BEFORE "THE ORIGIN OF SPECIES"

BY PROFESSOR ARTHUR O. LOVEJOY

THE UNIVERSITY OF MISSOURI

IN

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N this year of the Darwin centenary it is worth while to raise two questions which have, in the mass of literature elicited by the occasion, received less consideration than they merit. At what date can the evidence in favor of the theory of organic evolution-as distinct from the hypothesis of natural selection-be said to have been fairly complete: in other words, how early were the facts and principles from which the truth of that theory is now ordinarily inferred sufficiently known to all competent men of science, to require the inference, even though it was not, in fact, generally made? And by what English writer was a logically cogent argument for the theory first brought together and put before the public? The interest attaching to these questions is much more than merely historical. The answer to them will afford a sort of object-lesson in the logic of scientific reasoning. Here is a doctrine now accepted by all naturalists: at what point, in the century-long accumulation, through half a dozen separate sciences, of the evidences inclining to that doctrine, ought we to say that the balance of logical probability turned decisively in its favor? The inquiry will also be found, I think, to throw a somewhat instructive light upon the psychology of belief, and to show how far, even in the minds of acute and professedly unprejudiced men of science, the emotion of conviction may lag behind the presentation of proof.

By this time, no doubt-though it has not long been so every schoolboy knows that Darwin did not invent the theory of evolution. The Darwin centenary itself has served to remind the public of the names and works of at least some of the earlier protagonists of the doctrine of the elder Darwin, namely, of Lamarck, of Geoffroy St. Hilaire, of the author of the "Vestiges of the Natural History of Creation," and of Herbert Spencer. It is less commonly remembered, but perhaps not universally forgotten, that among English-speaking naturalists, the theory was a commonplace topic of discussion for two or three decades before 1859, and especially after the publication and immense circulation of the successive editions of Robert Chambers's "Vestiges," of which the first appeared in 1844. Geological text-books of the period referred to the "theory of transmutation of species" as

a matter of course, though usually only to reject it as an exploded hypothesis. Thus the "Elements of Geology," of Alonzo Gray and C. B. Adams, 1852, enumerates three theories which have been advanced respecting the origin of animal species: (1) Successive special creations; (2) "transmutation, which supposes that beings of the most simple organization having somehow come into existence, the more complex and the higher orders of animals have originated in them by a gradual increase in the complexity of their structures"; (3) generatio æquivoca of individuals and species. The first is adopted, but the second is discussed at greatest length; on it the authors remark that "those who have adopted the theory of transmutation have generally detached it from Lamarck's theory of appetency, and not attempted to explain how the process of transmutation goes on." The argument for evolution is similarly discussed and "refuted" in "Geological Science," a popular text-book by D. T. Ansted, F.R.S., 1854. To this refutation, indeed, the greatest of English geologists had devoted three chapters of his "Principles of Geology " before 1835.

But though such facts as these are, as I have said, now fairly familiar, the notion still widely prevails, even among biologists, that no serious proof of evolution either existed or had been published before the appearance of the "Origin of Species "-or at all events, before the late 1850's. Professor Joseph Le Conte,,indeed, in his "Evolution and Its Relation to Religious Thought," made it a reproach against both Lamarck and Chambers that they had unscientifically embraced the hypothesis before the evidence for it was ripe; and considered it fortunate for science that their notions died still-born, under the weight of the great authority of Cuvier and Agassiz. "I know," wrote Le Conte, "that many think with Haeckel that biology was kept back half a century by the baleful influence of Agassiz and Cuvier; but I can not think so. The hypothesis was contrary to the facts of science, as then known and understood. It was conceived in the spirit of baseless speculation, rather than of cautious induction; of skilful elabora

I quote from the reprint of 1854, p. 87.

The writer's copy of Lyell's "Principles" is the first American from the fifth London edition, 1837.

This opinion has, for example, been expressed by Poulton in his "Charles Darwin and the Theory of Natural Selection." "The paramount importance of Darwin's contributions to the evidences of organic evolution are [sic] often forgotten in the brilliant theory which he believed to supply the motive cause of descent with modification. Organic evolution had been held to be true by certain thinkers during many centuries; but not only were its adherents entirely without a sufficient motive cause, but their evidences of the process itself were erroneous or extremely scanty. It was Darwin who first brought together a great body of scientific evidence which placed the process of evolution beyond dispute, whatever the causes of evolution may have been" (p. 100).

* Second edition, 1905, pp. 33-35.

tion, rather than of earnest truth-seeking. Its general acceptance would have debauched the true spirit of science. . . . The ground must first be cleared . . . and an insuperable obstacle to hearty rational acceptance must first be removed, and an inductive basis laid." This last, Le Conte goes on to argue, was largely the work of Agassiz, opponent of evolutionism though he was. Now, it is, of course, undeniable that the premature adoption of a hypothesis is a sin against the scientific spirit, and that the chance acceptance by some enthusiast of a truth in which, at the time, he has no sound reason for believing, by no means entitles him to any place of honor in the history of science. But what constitutes prematurity in this particular matter? And was the evolutionary hypothesis "contrary to the facts of science, as known and understood " at any time after 1840?

The prevalent belief that it was is chiefly due to two things. The first is the fact that before 1859 few English naturalists of high standing accepted, and almost none publicly avowed, the theory of descent; whereas, after the publication of the "Origin," such notable names as Huxley, Lyell, Hooker and Asa Gray were speedily numbered among the disciples of the doctrine, and in the ensuing five years it was well upon its way towards its eventual complete triumph. The other source of the supposition that Darwin presented the first adequate grounds for believing in evolution is the express testimony of Huxley, whose paper on the reception of the "Origin of Species "5 has come to be the principal source of information on its subject. In that article, and in several letters and other writings, Huxley takes credit to himself for his rejection of the transformation-theory until he became acquainted with Darwin's work; and he never expressed any sentiment far short of contempt for Chambers's "Vestiges." He wrote in 1887:

I must have read the "Vestiges"... before 1846; but if I did, the book made very little impression on me, and I was not brought into serious contact with the " species" question until after 1850. . . . It seemed to me then, as now, that "creation," in the ordinary sense of the word, is perfectly conceivable.

I had not then, and have not now, the smallest a priori objection to raise to the account of the creation of plants and animals given in "Paradise Lost." ... Far be it from me to say that it is untrue because it is impossible. I confine myself to what must be regarded as a modest and reasonable request-for some particle of evidence that the existing species of animals and plants did originate in that way, as a condition of my belief in a statement which appears to me highly improbable. And, by way of being perfectly fair, I had exactly the same answer to give to the evolutionists of 1851-58. . . . The only person known to me whose knowledge and capacity compelled respect, and who was, at the same time, a thorough-going evolutionist, was Mr. Herbert Spencer. . But even my friend's rare dialectic skill and copiousness of apt illustration could not drive me from my agnostic position. I took my stand upon two grounds: Firstly, that at the time the evidence in favor of transmutation was wholly insufficient; secondly, that no suggestion respecting the causes of the Published as Ch. XIV. of "The Life and Letters of Charles Darwin."

...

transmutation assumed, which had been made, was in any way adequate to explain the phenomena. Looking back at the state of knowledge at the time, I really do not see that any other conclusion was justifiable. . . . As for the "Vestiges," I confess the book simply irritated me by the prodigious ignorance and thoroughly unscientific habit of mind manifested by the writer. If it had any influence at all, it set me against evolution. . . . Thus, looking back into the past, it seems to me that my own position of critical expectancy was just and reasonable. . . . So I took refuge in that tätige Skepsis which Goethe has so well defined; and, reversing the apostolic precept to be all things to all men, I usually defended the tenability of received doctrines, when I had to do with the transmutationists; and stood up for the possibility of transmutation, among the orthodox.

In this matter Huxley is assuredly a witness whose testimony should not lightly be set aside; for to his attainments as a naturalist he ordinarily joined singular logical acumen and rare openness of mind. Yet I think it possible to show that the passage just quoted gives a thoroughly misleading view of the logical status of the argument for evolution, as it existed in the light of the science of the period; that the attitude which Huxley assumed from 1850 to 1858 was contrary to all sound ideas of scientific method; and that he does the reputations of both Spencer and Chambers serious injustice. I shall attempt to establish these conclusions mainly by showing that the arguments and facts chiefly relied upon by Huxley himself and other early champions of transformism were entirely familiar and well authenticated from fifteen to twenty years before 1859, and had virtually all been clearly noted and pertinently used in the published evolutionary reasonings of Chambers or of Spencer. The truth is as the evidence to be adduced will make clear-that Huxley's strongly emotional and highly pugnacious nature was held back by certain wholly non-logical influences from accepting an hypothesis for which the evidence was practically as potent for over a decade before he accepted it as it was at the time of his conversion. These influences did not in Huxley's case, as they did in so many others, proceed from religious tradition or temperamental conservatism. But Huxley had unquestionably been strongly repelled by the "Vestiges." The book was written in a somewhat exuberant and rhetorical style; with all its religious heterodoxy, it was characterized by a certain pious and edifying tone, and was given to abrupt transitions from scientific reasoning to mystical sentiment; it contained numerous blunders in matters of biological and geological detail; and its author inclined to believe, on the basis of some rather absurd experimental evidence, in the possibility of spontaneous generation. All these things were offensive to the professional standards of an enthusiastic young naturalist, scrupulous about the rigor of the game, intolerant of vagueness and of any mixture of the romantic imagination with scientific inquiry, a little the victim, perhaps, of the current scientific cant about "Baconian induction," and quite incapable of

taking, towards any doctrine or movement, any attitude intermediate between contemptuous hostility and ardent partizanship. Full advantage, moreover, had been taken, by the eminent scientists who were. also champions of religious orthodoxy, of the faults of Chambers's book; they contrived very successfully to put about the impression that to be a "Vestigiarian" was to be "unscientific" and sentimental and absurd. These were three qualities which Huxley would have been peculiarly averse to being charged with. Finally, he seems to have been exasperated most of all by a single loose piece of phraseology that now and then recurs in the "Vestiges." Chambers, namely, was prone to speak of "laws" as if they were causes and, more particularly, as if they were secondary causes to which the "Divine Will" delegated its agency and control. To Huxley, from the beginning of his career, this hypostatizing fashion of referring to "laws of nature" was a bête noire; and in 1887 we still find him pursuing the author of the "Vestiges" with ridicule because of his "pseudo-scientific realism." He, therefore, in 1854, almost outdid the Edinburgh Review in the ferocity of his onslaught upon the layman who had ventured to put forward sweeping generalizations upon biological questions while

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"Science and Pseudo-science," 1887. Huxley's criticisms are curiously beside the mark. He argues that, whether you suppose that the Creator operates uniformly but directly according to such rules as he thinks fit to lay down for himself," or that "he made the cosmical machine and then left it to itself," in either case his "personal responsibility is involved" in every result into which this uniform operation works out. But Chambers, so far from denying this, was especially anxious to insist upon it. What he equally insisted upon, however, was the uniformity of this agency. When he spoke of the Creator as working "through" law, the expression, doubtless, was infelicitous; but his essential idea was plain and unexceptionable, viz., that neither organic nor inorganic phenomena "result from capricious exertions of creative power; but that they have taken place in a definite order, the statement of which order is what men of science term a natural law." These last words are Huxley's own, uttered in 1862, in an address before the Geological Society. It is, he added, logically possible to regard such a law as simply the statement of the manner in which a supernatural power has thought fit to act"; the main thing is that "the existence of the law and the possibility of its discovery by the human intellect" be recognized. This was exactly the essence of the view for which Chambers was contending. Huxley was so unduly enraged by a bit of unscientific looseness of language that he actually overlooked the important idea which that language was manifestly intended to express.

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'I have not had access to this article, published in the Medical and Chirurgical Review; but its character is sufficiently indicated in the correspondence of Huxley and Darwin. The former speaks of it as "the only review I ever have qualms of conscience about, on the ground of needless savagery." Darwin thought it "rather hard on the poor author "; and added a curiously mild intimation of his own belief: "I am perhaps no fair judge; for I am almost as unorthodox about species as the 'Vestiges' itself, though I hope not quite so unphilosophical" ("More Letters of Charles Darwin," I., 75).