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Evolution as a Heuristic
"If you will not let me treat the Art of Discovery as a kind of Logic, I must make a new name for it. Heuristic, for example" (William Whewell, quoted in Todhunter, 1970).Creationists continue to claim scientific validity for their version of "scientific creationism" and to demand its admission to the science classrooms of the nation's public schools. If both "models" are fairly presented, they say, students would overwhelmingly prefer the creation model over the evolutionary view.
This may be good propaganda, but the claim ignores the historical fact that we had just such a choice once before, and we chose evolution. What the creationists overlook is that before the publication of Origin of Species nearly everyone was a creationist — scientist and layman alike — and that a few years later, nearly everyone, scientist and layman alike, had become an evolutionist.
One of the major factors in this rapid transformation was the recognition that evolution provided a more rational way of organizing natural history than the traditional view of providential design. In particular, as a whole new way of looking at nature, it generated vast new areas for investigation not previously perceived. This heuristic, or exploratory, advantage of evolution has been little used in current debates, yet evolution continues to be an excellent heuristic, while creationism has no exploratory consequences at all. It is my purpose in outlining the heuristic argument at Darwin's time to provide additional perspective on today's debates.
The doctrine of special creation that dominated biological thinking in the century before Darwin was not basically different from so-called "scientific creationism" today. Both were derivatives of the faith in the absolute validity of the Genesis account of creation. But if one has belief in a final truth, then there is no need for further investigation, and this is the end of science. Darwin and his colleagues recognized this barrier to the search for the enlargement of human understanding of nature.
The capacity of evolutionary thinking to elucidate the facts is nowhere more effectively demonstrated than in the Origin itself where page after page is filled with observations demonstrating patterns and interrelationships of facts that could hardly have been noted without the guiding hypothesis of evolution. In the final chapter Darwin makes clear the heuristic function of his theory which will give a new sense of order to what it already known, and open vast prospects for new understanding.
[W]hen we regard every production of nature as one which has had a history; when we contemplate every complex structure and instinct as the summing up of many contrivances, and each useful to the possessor... when we thus view each organic being, how far more interesting... will the study of natural history become!Rules of classification, he added, will become simpler, embryology will reveal structure, geographical distribution will be illuminated by increased geological knowledge, changes of climate, and so on. All these and many more areas of human curiosity will be freshly perceived through the perspective of descent with modification.
In addition to listing the benefits of his evolutionary perspective, Darwin also noted the negative effects of the prevailing doctrine of special creation. For too many years, naturalists had viewed species as specially created to occupy the niches into which they are clearly adapted. But this traditional view could now be seen for what it was, a way "to hide our ignorance under such expressions as the 'plan of creation', 'unity of design', &c., and to think that we give an explanation when we only restate a fact." And the sterility of such views is further disguised by assuming a "reverent silence" instead of seeking causal explanations (C Darwin, p 482-3). It is, after all, the office of science to investigate nature, not merely to admire it.
Darwin's earliest confidant, botanist Joseph Hooker, resisted for 14 years Darwin's arguments for descent with modification. It was only while Darwin was rapidly writing Origin that Hooker indicated that he was going to organize his "Essay on Australian Flora" according to the new views. Darwin was delighted and wrote to Hooker, July 13, 1838 emphasizing the opportunities the theory created.
You cannot imagine how pleased I am that the notion of Natural Selection has acted as a purgative on your bowels of immutability. Whenever naturalists can look on species changing as certain, what a magnificent field will be open — on all the lines of variation — on the genealogy of all living being — in their lines of migration, &c., &c. (F Darwin 1837:485).And Hooker in turn expresses the heuristic advantages of evolu-tion when explaining his intentions to his botanical colleague William H Harvey.
What I shall try to do is, to harmonize the facts with the newest doctrines, not because they are the truest, but because they do give you room to reason and reflect at present, and hopes for the future, whereas the old stick-in-the-mud doctrines of absolute creations, multiple creations... are all used up, they are so many stops to further enquiry; if they are admitted as truths, why there is an end of the whole matter, and It is no use hoping ever to get to any rational explanation of origin or dispersion of species — so I hate them (Huxley 1918:481-2).The deadening effects of a strong commitment to special creation is nowhere more clearly illustrated than by Adam Sedgwick in his 1860 review of Origin.
Change the conditions of life, he admits, and old species would die out, and new species might have room to come in and flourish. But how, and by what causation? I say by creation. But, what do I mean by creation? I reply, the operation of a power quite beyond the powers of a pigeon fancier, a cross-breeder, or hybridizer; a power I cannot imitate or comprehend; but in which I can believe. (Quoted by Hull 1973:161).By declaring his faith in a "power I cannot imitate or comprehend", Sedgwick has set the problem of species outside the scope of human inquiry, and in Hooker's words, "there is an end of the whole matter."
In contrast to the stultifying effects of creationism, Thomas Huxley saw in Darwin's work the fulfillment of the highest aims of science and humanity itself.
The known is finite, the unknown infinite; intellectually we stand on an islet in the midst of an illimitable ocean of inexplicability. Our business in every generation is to reclaim a little more land, to add something to the extent and the solidity of our possessions. And even a cursory glance at the history of the biological sciences during the last quarter of a century is sufficient to justify the assertion, that the most potent instrument for the extension of the realm of natural knowledge which had come into men's hands, since the publication of Newton's "Principia," is Darwin's "Origin of Species" (F Darwin 1887: 557).An additional century has not altered the validity of Huxley's assessment, and the creationism so vigorously rejected then still has no place in the intellectual toolbox of science today.
SummaryA good scientific theory provides not only a rational organization of factual information, essential for effective pedagogy, but also stimulates questions that lead to further investigations, new factual knowledge of nature, and modification and expansion of the theory. Evolution continues to do this even as it has been modified. Creationism has NO exploratory consequence and thus has no justifiable place in science classrooms.
ChallengeIf this heuristic function of evolution and all scientific theories can be conveyed to the general public, surely evolution will be generally supported as good science, and creationism recognized as not science at all. To meet this challenge we need to develop and present a series of specific examples of how evolutionary thought has led directly to the discovery of valuable knowledge in the biological sciences. Examples from agriculture and medicine would perhaps be most persuasive to those who determine classroom curricula: school boards, school administrators, teachers, and parents. All of us who support evolution in science education should take up this challenge.
ReferencesDarwin C. On the Origin of Species: A fac-simile of the first edition. NY: Atheneum, 1967.
Darwin E (editor). The Life and Letters of Charles Darwin. Vol 1. NY: D Appleton and Company, 1887.
Hull DL. Darwin and His Critics: The Reception of Darwin's theory of Evolution by the Scientific Community. Cambridge (MA): Harvard University Press, 1973.
Huxley L. Life and Letters of sir Joseph Dalton Hooker. New York: Appleton, 1918.
Todhunter I. William Whewell, D.D., master of Trinity College, Cambridge; An account of his writings with selections from his literary and scientific correspondence. New York: Johnson Reprint Corp, 1970.