But the main case for taking Paley seriously lies in his formulation and refutation of opposing visions. Anyone can spin out a rationale for an idée fixe, but a well-crafted system requires both full analysis and principled denial of alternatives. Natural Theology merits our respect, and becomes a key document for this chapter on the history of functionalism vs. formalism, because Paley recognized the structuralist alternative and provided a coherent defense. [Page 267] His arguments span two chapters (15 on relations and 16 on compensations), treating the phenomenon always viewed as crucial and primary by advocates of structural constraint — stable correlations among parts of the body.
Since Paley's main argument holds that intricate contrivance implies a contriver, two main rebuttals might be offered in principle: (1) the adaptations exist, but they originated by a natural process of evolution, not by creative acts of a deity; (2) organisms were created, but adaptation does not permeate or even dominate their form.
Since Paley never imagined the alternative of natural change by selection or weeding out, he confines his refutation of adaptive evolution to the “Lamarckian” principle of use and disuse. (I doubt that Paley, writing in 1802, knew Lamarck's work directly, since his French colleague had just begun to publish evolutionary views. But use and disuse, as an item of folk wisdom, frequently entered the arguments of evolutionists.) Paley begins empirically by pointing out that centuries of disuse do not cause organs to disappear, though modesty leads him to cloak a classic case entirely in untranslated Latin: “The mammae of the male have not vanished by inusitation; nee curtorum, per multa saecula, Judaeorum propagini deest praeputium” [nor has the foreskin of Jews become any shorter in offspring through many centuries of circumcision] (p. 446).
Paley then asks, more theoretically, how any natural evolution of useful structures could be attributed to a stimulus structurally unrelated to biological form, and often inorganic. The eye is a contrivance for perceiving light, but light cannot make an eye. “Yet the element of light and the organ of vision, however related in their office and use, have no connection whatever in their original. The action of rays of light upon the surfaces of animals has no tendency to breed eyes in their heads. The sun might shine forever upon living bodies without the smallest approach towards producing the sense of sight” (p. 317).
When two structures have been similarly fashioned for a common purpose by a strengthening of one and a weakening of the other (the subject of Paley's “compensations” in chapter 16), natural adjustment by evolution might be defended (as when an elephant elongates its trunk to compensate a shortness of neck). But Paley denies this “best case” by the standard argument that intermediary stages could not be well designed: “If it be suggested, that this proboscis may have been produced in a long course of generations, by the constant endeavor of the elephant to thrust out his nose, (which is the general hypothesis by which it has lately been attempted to account for the forms of animated nature), I would ask, how was the animal to subsist in the meantime, during the process, until this elongation of snout were completed? What was to become of the individual, whilst the species was perfecting?” (p. 299).
If the first alternative (adaptation, but by evolution) can be thus refuted, how can the second possibility (creation, but with adaptation secondary or absent) be dismissed as well? Paley now meets the formalist alternative face-to-face — [Page 268] and rejects this last challenge with three arguments that, taken together, develop his strongest case for adaptationism (the first two remain in prominent use today):
1. Formalists do not deny the evident utility of most organic structures. The focus of their argument, rather, rests upon a claim for temporal and causal primacy (homology based upon historical order for evolutionists, or similarity based upon repeated themes in manufacture for creationists). Adaptationists hold that structures must evolve or be fashioned for utility: functional needs come first, and form follows. Formalists argue, on the other hand, that morphology may arise for reasons other than use, with later “uptake” of function as subsidiary: that is, form comes first, and organisms may then discover usages. In a remarkable passage, showing his grasp of this fundamental alternative (now being reasserted as the basis for revival of interest in constraint among modern evolutionists), Paley admits that the formalist argument must be acknowledged as “intelligible”: “To the marks of contrivance discoverable in animal bodies, and to the argument deduced from them, in proof of design, and of a designing Creator, this turn is sometimes attempted to be given, viz. that the parts were not intended for the use, but that the use arose out of the parts. This distinction is intelligible. A cabinet-maker rubs his mahogany with fish-skin; yet it would be too much to assert that the skin of the dogfish was made rough and granulated on purpose for the polishing of wood, and the use of cabinet makers” (p. 72).
Paley's refutation invokes the classic response: the formalist argument will work for simple structures like fish-skin, but not for complex organs, composed of multiple parts, all apparently adjusted for current function. “Is it possible to believe that the eye was formed without any regard to vision; that it was the animal itself which found out, that, though formed with no such intention, it would serve to see with; and that the use of the eye, as an organ of sight, resulted from this discovery, and the animal's application of it?” (p. 73).
2. The first argument epitomizes a conceptual mainstay of formalism, but the empirical foundation of structuralist morphology has always depended more strongly upon correlation among parts of an organism, buttressed by the inference that structural relations, rather than utility, establish the linkage. Again Paley provides the classic functionalist refutation, still prominently in use. The correlations, he argues, do not arise by formal necessity, or “laws of growth,” but as coordinated adaptations, each separately useful and required for good design. Swans have long necks and webbed feet for reasons of common function, not “necessary connection”: “The long neck, without the web foot, would have been an incumbrance to the bird; yet there is no necessary connection between a long neck and a webfoot. In fact they do not usually go together. How happens it, therefore, that they meet, only when a particular design demands the aid of both?” (p. 293).
Paley then discusses a favorite example of British adaptationists since John Ray, and a pest in British gardens from time immemorial: the mole. “From soils of all kinds the little pioneer comes forth bright and clean. Inhabiting [Page 269] dirt, it is, of all animals, the neatest” (p. 294). Paley defends adaptation with an explicit rejection of the strongest argument for constraint (what Darwin would later call “correlation of growth”). Recalling his opening metaphor, Paley writes: “Observe then, in this structure, that which we call relation. There is no natural connection between a small sunk eye and a shovel palmated foot. Palmated feet might have been joined with goggle eyes; or small eyes might have been joined with feet of any other form. What was it therefore which brought them together in the mole? That which brought together the barrel, the chain, and the fusee, in a watch: design; and design, in both cases, inferred, from the relation which the parts bear to one another in the prosecution of a common purpose” (p. 296).
3. But what can an adaptationist say about the overarching homologies of broad taxonomic structure? Are these widespread properties not formal constraints, logically prior to any subsequent utility forged by specific tinkering with such common elements? (We certainly acknowledge such priority today, but we also recognize Darwin's incisive argument that these “phyletic” constraints may have arisen as ancestral adaptations — see last section. Paley enjoyed no conceptual access to this legitimate adaptationist exit from the dilemma.)
In a clever twist of argument, Paley turns homology to the cause of adaptation in two steps:
(1) God devised general plans with foreknowledge of their requisite modification for specific purposes in individual species. For if these grand homologies had been generated automat
ically by abstract laws of nature, with no reference to final causality, how could such widespread structures be so subtly subject to such varied adaptation in the service of so many particular modes of life? “Whenever we find a general plan pursued, yet with such variations in it, as are, in each case, required by the particular exigency of the subject to which it is applied, we possess, in such a plan and such adaptation, the strongest evidence, that can be afforded, of intelligence and design ... If the general plan proceeded from any fixed necessity in the nature of things, how could it accommodate itself to the various wants and uses which it had to serve, under different circumstances, and on different occasions?” (Paley, 1803, p. 227).
(2) Yet Paley recognized the potential circularity in this claim, if taken by itself. To be sure, once such homologies have been established, they may be examined for susceptibility to adaptive modification. But why did God proceed in this manner at all? Why didn't he just make each species from scratch, optimally suited for its own peculiar mode of life? Why bother with common plans at all, when creatures sharing the plans work so differently? Here, at the crux of his difficulty, Paley invokes a venerable solution that has always (both then and now) struck critics as at least slightly sophistic (in the sense that any potential refutation could be so “accommodated,” thus making the theory irrefutable, untestable, and therefore useless): God shows his greatness by limiting his own power with ordered principles (secondary causes based on natural laws) and structural designs (grand homologies): [Page 270]
God, therefore, has been pleased to prescribe limits to his own power, and to work his ends within those limits. The general laws of matter have perhaps the nature of these limits . . . These are general laws; and when a particular purpose is to be effected, it is not by making a new law, nor by the suspension of the old ones, nor by making them wind and bend and yield to the occasion (for nature with great steadiness adheres to, and supports them), but it is, ... by the interposition of an apparatus corresponding with these laws, and suited to the exigency which results from them, that the purpose is at length attained. As we have said, therefore, God prescribes limits to his power, that he may let in the exercise, and thereby exhibit demonstrations of his wisdom (p. 43).
After all, adaptationism only requires that organic designs be complex and work well, not that they embody perfection: “Contrivance, by its very definition and nature, is the refuge of imperfection. To have recourse to expedients implies difficulty, impediment, restraint, defect of power” (pp. 41-42).
Paley's closing paean, following this last statement, exalts adaptation as logically necessary, quite apart from any factual validation. Contrivance not only sets the dominant pattern of empirical nature. Such good design also represents the only way that God could proclaim his existence in principle! To quote the passage of page 119 once again:
It is only by the display of contrivance, that the existence, the agency, the wisdom of the Deity, could be testified to his rational creatures. This is the scale by which we ascend to all the knowledge of our Creator, which we possess, so far as it depends upon the phenomena, or the works of nature. Take away this, and you take away from us every subject of observation, and ground of reasoning . . . Whatever is done, God could have done, without the intervention of instruments or means: but it is in the construction of instruments, in the choice and adaptation of means, that a Creative Intelligence is seen. It is this, which constitutes the order and beauty of the universe (p. 42).
Paley's argument coheres, yet sounds a peculiarly limited range of notes — the reason for my “sand painting” metaphor of page 262. Paley does mention the grand homologies that underlie all taxonomy — but only in a paragraph or two, and only to offer an adaptationist riposte. He does formulate the structuralist argument based on correlation — but only in passing reference, and only for refutation. We might be tempted to offer the Philistine's retort — “oh well, Paley was just a philosopher; what did he know about real biology?” But modern disciplinary boundaries did not exist in 1800, and great biologists, including Darwin, valued Paley above all other books in natural history. Moreover, as I shall show in the next section, a fine working biologist like Agassiz could present the other side with equally uncompromising exclusivity.
We must therefore grasp Paley's restricted compass as a consciously-chosen vision of life's substance and meaning. As such, we may utilize, for our own [Page 271] instruction, a position so unsullied by nature's real complexities. We know that life cannot work at such a conceptual extreme, but any consistent and well-argued defense of such an edge remains fascinating — at least in illustrating a set of mental habits that still motivates scientists. Just as we learn to grasp nature through controlled and simplified cases (the experimental method), so may we also comprehend mind by its defense of coherence at the philosophical endpoint of a continuum.
LOUIS AGASSIZ AND CONTINENTAL FORMALISM: PRAISING GOD IN THE GRANDEUR OF TAXONOMIC ORDER
Louis Agassiz, as the first permanent immigrant among great European biological theorists, became the symbol and actuality of maturation and prestige for American natural history in the mid 19th century. Romantic mythology proclaims that he ventured forth as an intrepid pioneer in a quest for pristine knowledge and uncharted species. In fact, Agassiz's primary reasons for resettlement were far more mundane — escape from trouble and hope for a new beginning. He had suffered the two classic reversals of personal misfortune after years of intellectual triumph: bankruptcy (when his lithographic press, initially established to print the plates for his Poissons fossiles, failed) and familial strife (when his wife moved out after he had turned their home into a factory and boarding house for workers at his press). In any case, whatever the complex motives, Agassiz's decision to settle permanently at Harvard established a happy incongruity within an expanding and accepting culture — a great francophone theorist, with traditional continental attitudes, living in Yankee Boston.
Agassiz (1807-1873) came to America with grand plans to invest his boundless energy in systematic work on undescribed native faunas, following his own maxim: “study nature, not books.” But, as a consummate academic politician and promoter, he became sidetracked over the years (an old story, as deep as human nature itself), and published little technical work during his last two decades. The frustration in this familiar tale of good intentions lies best exposed in Agassiz's grandest project and its failure.
Early in the 1850's, he announced plans for a lavish 10-volume work to be called The Natural History of the United States. He gathered more than 2,000 paid subscriptions in advance, and began collection (for an initial monograph on turtles) with his old and characteristic zeal. But he soon bogged down — permanently. Only four volumes ever appeared (with the descriptive and taxonomic work largely done by others), and he talked less and less about his grand design as the years ticked away. Nonetheless, while still imbued with initial enthusiasm, he wrote, as a book-length introduction to volume 1, his finest theoretical work, the Essay on Classification. Published in 1857, and revised in 1859 (ironically just 3 months before publication of Darwin's Origin, the book that would undermine the central premise of Agassiz's work), the Essay on Classification stands as a unique and incongruous document — a statement of natural theology in the highest tradition of [Page 272] continental formalism, published in the most English of American cities. Agassiz never mentions Paley by name, but his volume presents an almost perfect counterpoise to Paley's Natural Theology from the other pole of the great dichotomy in approaches to form — particularly, in this case, to the question of how an omnipotent God would manifest his glory in nature.
Modern supporters of systematics, in a world increasingly dominated by trendier forms of biological research, often feel beleaguered, and therefore impelled to provide a wider rationale for pursuing classification, an enterprise unfairly burdened with such epithets as “stamp collecting” by a miscomprehending public. Today, the rationale for systematics
tends to be given — quite legitimately of course — in terms of our current crises in environmental deterioration and declining biodiversity. Yet if any systematist ever yearned for a maximally grand rationale for his chosen profession, he could not find, or even imagine, a more audacious document than Agassiz's Essay on Classification. (Unfortunately, changing philosophies and increasing knowledge have rendered Agassiz's argument obsolete, but we may still sense, and should still admire, the style and grandeur of his claim.)
In baldest terms, and from a Platonic perspective (with organisms construed as temporary, material incarnations, representing the permanent and transcendent mental structures of an overarching creative force), Agassiz argues that taxonomy should be regarded, in principle, as the highest of the sciences. For species embody ideas in God's mind; and actual organisms then became transient configurations that represent, or incarnate, these ideas. Relationships among species, as expressed in classification, therefore reveal the structure of God's thought, for if each species denotes a divine idea, then their interconnections in taxonomy display the order of God's mentality.
Agassiz poses the key question: “Are these divisions artificial or natural? Are they the devices of the human mind to classify and arrange our knowledge in such a manner as to bring it more readily within our grasp and facilitate further investigations, or have they been instituted by the Divine Intelligence as the categories of his mode of thinking?” (1857, pp. 7-8). He then provides his firm answer: “To me it appears indisputable, that this order and arrangement of our studies are based upon the natural primitive relations of animal life, — those systems [of classification] . . . being in truth but translations, into human language, of the thoughts of the Creator.”
The Structure of Evolutionary Theory Page 44
