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The Scientific Imagination

Although the Origin of Species is supposed to have burst like a bombshell upon the unsuspecting scientific world, to say nothing of the lay world, the public debate between Gray and Agassiz on the subject of evolution started several months before the appearance of the Origin. Indeed, the issue was joined two years earlier, with the publication of Agassiz’ “Essay on Classification,” which is an almost point-by-point refutation of the main arguments of the Origin. Refutation, and at the same time anticipation of the Origin. For Agassiz was as much a progenitor of Darwin as an antagonist. The burden of Agassiz’ five-volume work on fossil fishes was, as he put it, the “correspondence between the succession of fishes in geological times and the different stages of their growth in the egg.” This parallelism between paleontology and embryology Darwin claimed to be “by far the strongest single class of facts” in favor of his theory. When Huxley, several years before the Origin, disputed one of Agassiz’ favorite examples of such parallelism, Darwin confessed that “though I saw how excessively weak the evidence [of Agassiz] was, I was led to hope in its truth.” Five years later, describing Agassiz’ theory in the first edition of the Origin, he combined skepticism and hope in equal proportions:

I must follow Pictet and Huxley in thinking that the truth of this doctrine is very far from proved. Yet I fully expect to see it hereafter confirmed, at least in regard to subordinate groups. For this doctrine of Agassiz accords well with the theory of natural selection.

Although subsequent years brought no further confirmation of Agassiz’ theory and no reason to discount the evidence of Pictet and Huxley, the final edition of the Origin, published in 1872, saw the triumph of hope over doubt. The theory was then ascribed to “Agassiz and several other highly competent judges”; the sentence about Pictet and Huxley was omitted; and the passage ended confidently: “This view accords admirably well with out theory.”

The affinity between Darwin and Agassiz went far beyond this one theory. As Gray ‘himself said: “There is a significant correspondence between the rival theories [Darwin’s Natural Selection and Agassiz’ anti-evolutionism] as to the main facts employed. Apparently every capital fact in the one view is a capital fact in the other. The difference is in the interpretation.” The point should be noted by biographers of Darwin, who almost invariably present the Voyage of the Beagle as a triumphant voyage of discovery. Every mention of a fossil, every allusion to a resemblance between a fossil and a living species, every reference to the geographical distribution of species, the relations of species in the same area or in different areas, the range of variations within species—all these are pounced on as premonitions of the Origin. And the assumption is made that Darwin not only discovered the theory of natural selection as a logical or necessary deduction from these facts, but that he discovered the facts themselves. Yet, as Gray admitted and Agassiz demonstrated, these facts about fossils, embryology, homology, geographical distribution, etc., were not only the common property of all naturalists; they could be used as effectively against the theory of natural selection, indeed against any theory of evolution, as for it.

Where Agassiz differed from Darwin was in denying the utilitarian and functional character of these facts. The correspondence between fossil forms and living embryos, or between species widely disparate in time and place, suggested to him a “unity of plan”—but a unity of plan revealing no purpose or use except to testify to the will of God. For what utilitarian function, he protested, was served by the fact that the embryo of a living egg re-capitulated the ancient succession of fossils? Why, in the name of utility, should an arctic species differ only in the smallest details from a tropical one, while in important respects exhibiting the same unity of plan? And why should species exist only as “categories of thought”—for Agassiz agreed with Darwin that species had no material reality—if it were not to demonstrate the “intellectual connection” imposed by God upon nature?

It is curious that Agassiz, who generally figures in the history of Darwinism as the champion of religion against science, should have been remembered by Henry Adams as the only professor who contributed to his education during four years at Harvard, and by William James as the scientist who taught him to love the concrete and to distrust the abstract. It is also curious that the very qualities admired by Adams and James, qualities that made him one of the most respected scientists of his generation, should have been so largely responsible for his opposition to theories of evolution. His “Essay on Classification” was as much an attack on the metaphysics of Natural Theology as on the science of the evolutionists. It was the teleological character of both, the ascription of purpose and design to nature, that he condemned as a violation of the true facts of nature and of the true dignity of God.

There is little doubt that the theory of Natural Selection, as presented in the Origin and as understood both by Darwin and by most of his disciples, was essentially teleological. Thus Asa Gray, in his enthusiastic review of the book, praised it for showing how the system of nature had “received at its first formation the impress of the will of its Author, foreseeing the varied yet necessary laws of its action throughout the whole of its existence, ordaining when and how each particular part of the stupendous plan should be realized in effect.” Darwin was so pleased with Gray’s other articles on the Origin that he undertook to publish them as a pamphlet, and it was he who suggested the sub-title: “Natural Selection not inconsistent with Natural Theology.” He also added to the second edition of the Origin a motto from Bishop Butler to the same effect. (Paley already appeared in the text in support of the view that “no organ will be formed…for the purpose of causing pain or for doing an injury to its possessor.”) Later, to be sure, particularly under the prompting of Huxley, (who, however, himself professed to believe in a “wider teleology” of natural law), Darwin began to suspect that Gray was assigning too much power to God and too little to Natural Selection, and that the universe was not entirely beneficent in its design. But his suspicions of Natural Theology did not extend to teleology, and when, as late as 1874, Gray congratulated him for having restored teleology to science, Darwin thanked him warmly: “What you say about Teleology pleases me especially, and I do not think any one else has ever noticed the point.”

If the recent selection of Darwin’s writings by Stanley Edgar Hyman is superior to most others, it is because it was compiled by a literary critic whose method is peculiarly well suited to eliciting motifs, such as the teleological one, that were paramount in the original conception of Darwinism and that have since been generally ignored. In an essay published last year in The Tangled Bank. Hyman undertook to consider Darwin’s writings as “imaginative organizations, as though they were poems.” The results of that undertaking obviously inform the present selection, and it is unfortunate that he could not reprint the whole of that essay as a commentary on this selection. For the essay is a notable contribution to the “Art of Science” and a salutary corrective to the ideas of most scientific historians.

Mr.Hyman, coming at Darwin from a new direction, by-passes the usual myths and conventions. He explains why it was the Origin. rather than its many predecessors and anticipators, that produced the revolutionary effect it did: “This enormous effect was achieved by the power of scientific argument, that is by the book’s rhetorical organization.” He quotes the opening words of the final chapter of the Origin: “As this whole volume is one long argument…” He observes that “the evidence to establish the idea of evolution by natural selection inductively was not really available in 1859,” that many of Darwin’s processes turn out on closer examination to be plausible hypotheses, and his causes tautologies,” and that the vehemence of the controversy hardly suggested “the characteristic effect of a scientific demonstration.” “Perhaps the most surprising thing in the Origin,” he comments, “is that it repeatedly calls not for an act of understanding but for an act of imagination.”

And he gets bolder as he goes on. If the characteristic effect of the Origin was not that of “scientific demonstration,” it was that of a “dramatic poem,” a “tragic drama.” Even more, it was a poem of a special kind, “something like a sacred writing, a scripture.” Darwin’s metaphors and imagery were consistently teleological, “In reality, of course, Darwin’s teleology is as sacred and supernatural as Paley’s but with all seeing Mother Nature substituted for God the Father.” “The appeal of the Origin is not only for imagination, wonder, marvel, rather than ratiocination, but ultimately for belief and faith.” And its rapid acceptance confirmed its religious character, for it followed the typical sudden and dramatic pattern of religious conversion, rather than the slow, laborious process generally associated with scientific demonstration and persuasion.

All this may sound wild and bizarre, the playful fancies of a littérateur. Yet to one who has studied Darwin closely, they are obvious, literal truths. If Mr. Hyman has any failing, it is in not being daring enough. It is unfortunate that, having come so far, he has not gone further, and that he has contented himself with minor literary insights and refrained from significant judgments of a scientific or philosophical order. Thus he does not take seriously enough his own remarks about the rhetorical nature and effect of the Origin. When he says that the book called for an act of “imagination” rather than “understanding,” he is too easily satisfied with such familiar varieties of imagination as the hypostatization of nature or the personification of plants and insects. Yet he has presented evidence enough, and there is far more of the same kind, to suggest that the act of imagination was a response not to this or that passage of poetic writing but to the entire rhetorical structure of the Origin. He quotes Asa Gray: “The interest for the general reader heightens as the author advances on his perilous way and grapples manfully with the most formidable difficulties.” But he is too intent upon his own quest for metaphors and images to examine the perilous way taken by Darwin in his “mythic quest.” (It is significant that Mr. Hyman’s selection includes only the briefest excerpt from the Origin, offering instead an early, barer sketch of the theory.)

One of Darwin’s contemporaries analyzed the nature of the “one long argument” of the Origin: first the reader was asked to concede the “mere possibility of imagining” a given proposition; having made this concession he then found that the possibility of imagining the proposition was itself put forward as a reason for supposing the probable truth of the proposition; the probable truth of this proposition, in turn, was taken as the basis for the possibility of imagining another proposition, and so on, ad seriatim. By this Alice-in-Wonderland logic, the compounding of possibilities led not to a diminution of probability, as in conventional logic, but to an augmentation of probability. And the reader became more and more committed to the theory as he allowed his imagination to be more and more committed to conjecture. All the difficulties Darwin so manfully grappled with were in fact overcome only in imagination. When he was confronted with what he himself took to be the “gravest and most obvious” objection to his theory, his only reply was to propose an “imaginary illustration” and a “hypothesis.” And when even such imaginary solutions failed him, he made the failure itself an accomplice:

Does not the difficulty rest much on our silently assuming that we know more than we do? I have literally found nothing so difficult as to try and always remember our ignorance. I am never weary, when walking in any new adjoining district or country, of reflecting how absolutely ignorant we are why certain old plants are not there present, and other new ones are, and others in different proportions…Certainly a priori [i.e., according to his theory] we might have anticipated that all the plants anciently introduced into Australia would have undergone some modification; but the fact that they have not been modified does not seem to me a difficulty of weight enough to shake a belief grounded on other arguments.

This is surely not the “scrupulous regard for negative evidence” that Mr. Hyman refers to and that idolators of science celebrate. It is, however, one path taken by the scientific imagination—and not, perhaps, the most devious one.

Another instance: Mr. Hyman points out that Darwin was conducting experiments with garden peas at exactly the same time as Gregor Mendel, but that he failed to deduce from these experiments the laws of genetics because he did not attend to the same facts as did Mendel. Variations of color provided Mendel with his chief clue; but Darwin was too engrossed with those variations suggesting conflict, struggle, and competition to pay attention to so passive a characteristic as color. Elsewhere Mr. Hyman contrasts the dramatic accounts of the “war of nature” and “struggle for existence” in the Origin with the frigidly neutral formulations of modern genetic-oriented Darwinians. In both cases, however, he fails to draw any significant conclusions from these contrasts. If he seriously followed through on his own principle that metaphor, imagery, and rhetoric are not a “superficial matter of ‘style’,” but rather “the work of the moral imagination, imposing order and form on disorderly and anarchic experience,” he would have had to conclude that Darwin and Mendel ordered nature in quite different ways, and that Natural Selection and genetics are not as easily reconciled as the neo-Darwinians suppose.

William James once said: “Different minds have a scent for different kinds of truth.” Philosophers of science expounding upon the “art of science,” historians of science reminding us of the confusion and ambiguities involved in actual scientific discoveries, literary critics examining scientific texts as works of “moral imagination”—all these may help us appreciate the cogency of James’s remark.

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