teleology - yesterday, today, and tomorrow

Stud. Hist. Phil. Biol. & Biomed. Sci, Vol. 31, No. 1, pp. 213–232, 2000Pergamon 2000 Elsevier Science Ltd. All rights reserved.

Printed in Great Britain1369-8486/00 $ - see front matterwww.elsevier.com/locate/shpsc

Teleology: Yesterday, Today, andTomorrow?

Michael Ruse*

Teleological explanations in evolutionary biology, from Cuvier to the present (andinto the future), depend on the metaphor of design for heuristic power and predic-tive fertility.

There is something distinctive about biological explanation, particularly about evol-utionary biological explanation (Nissen, 1997). In the physical sciences, it is inap-propriate to ask questions which demand explanations making reference to futureevents. One would never ask a question about the function or purpose of the moonanticipating a response that the function or purpose was some future happeningsuch as causing the tides to ebb and flow. It is true indeed that the moon doescause tides to ebb and flow, but that is not its intended functional purpose. In thebiological sciences, however, particularly in those areas dealing with evolution, itis fully appropriate to ask questions of this ilk. One can ask about the function orpurpose of the diagonal plates down the back of the dinosaur Stegosaurus, andvalid responses are that the plates exist in order to scare off predators or to attractmates or (as is thought highly probable today) to help with heat regulation(Lewontin, 1978).

Forward-looking explanations of the kind just given are referred to as ‘teleologi-cal’. It is my intention to explore precisely why such teleological explanations arethought appropriate in evolutionary biology, but not in the physical sciences. Asa supplementary question, I ask whether or not one might expect such teleologicalexplanations to exist indefinitely. Or are they mere props, doomed to extinction asevolutionary biology develops and matures? Because I am myself an evolutionistand because I believe that answers to the present and future are often to be foundin the past, I will structure this paper into three parts. The first will deal with pre-evolutionary biological thought in a teleological mode. The second will deal with

* Department of Philosophy and Department of Zoology, University of Guelph, Guelph, Ontario, Can-ada N1G 2W1.

Received 13 April 1999; in revised form 4 November 1999.

PII: S1369-8486(99)00046-1

213

214 Studies in History and Philosophy of Biological and Biomedical Sciences

teleological explanations as they exist in evolutionary thought, particularly as theyexist in evolutionary thought after the publication in 1859 of Charles Darwin’sOrigin of Species. The third and final part will look at questions of structure andmeaning, and try to throw light on the future fate of biological/teleological expla-nations.

1. Pre-evolutionary Teleology

From our perspective, the most important pre-Darwinian non-evolutionary bio-logical thinker was the early nineteenth-century French scientist, the father of com-parative anatomy, Georges Cuvier (1813, 1817). He was not the first teleologist,for indeed teleological thought goes back to the Greeks. Aristotle was a majorinfluence on Cuvier, although probably a more immediate influence was the eight-eenth-century German philosopher Immanuel Kant. (Cuvier was born in a borderstate and educated in Germany.) But whatever the sources, teleological thought isabsolutely central to Cuverian biology. He argued that the key organizing principleof living forms is that they are not just randomly thrown together. They exist ratherin a self-coordinating fashion, with the parts integrated towards the well-being andfulfilment of the whole.

Cuvier referred to this organizing principle as the ‘Conditions of Existence’,defining it formally thus:

As nothing may exist which does not include the conditions which made its existencepossible, the different parts of each creature must be coordinated in such a way asto make possible the whole organism, not only in itself but in its relationship to thosewhich surround it, and the analysis of these conditions often leads to general laws aswell founded as those of calculation or experiment. (Cuvier, 1817, vol. 1, p. 6; quotedin Coleman, 1964, p. 42)

The conditions-of-existence principle played a major part in Cuvier’s thinking,because he thought that through it he had a method of investigation which wouldenable him to bring order and understanding to the biological world. An order andunderstanding no less than his contemporaries were bringing to the worlds of phys-ics and chemistry. In particular, Cuvier argued that precisely because organismsare integrated and directed towards the well-being of the whole—because theyfunction in such a way as to serve the end of the complete organism—we candeduce from some few parts of the organism how the whole must function, andhence what shape it must have had. Thus, Cuvier argued that if by chance onewere given just a tooth of an unknown mammalian form, one could proceed fromthere to infer the life style and habits and even the structure of the whole organism.Such tooth would at once reveal whether the organism was meat-eating or herbivor-ous. And if, let us suppose, it prove to be meat-eating, one can immediately excludethe possibility that the organism has hooves like a horse, or a stomach like a cow.Rather it must have the attributes necessary for hunting and catching prey, as well

215Teleology: Yesterday, Today, and Tomorrow?

as for then tearing the victims apart and eating and digesting large chunks of rawflesh. One or a few parts thus dictate the nature of the whole: and note that thekey underlying principle is one of teleological thought. Because the parts exist forthe future benefit of the organism, one can spell out and infer the nature of thesevarious parts from just a few sample items.

Not only did Cuvier think that his teleological stance gave him a method ofinferring the nature of unknown organisms, but he believed also that this ledstraight to a natural ordering of organisms. Cuvier argued that in practice the ‘Con-ditions of Existence’ translates into something which he knew as the ‘Correlationof Parts’. ‘Hence none of these separate parts can change their forms without acorresponding change in the other parts of the same animal, and consequently eachof these parts taken separately, indicates all the other parts to which it has belonged’(Cuvier, 1813, pp. 90–1).

From this correlation, one can infer that organisms fall naturally into a fixednumber of groups and subgroups. This comes through the ‘Subordination ofCharacters’.

The parts of any animals possessing a mutual fitness, there are some traits of themwhich exclude others and there are some which require others; when we know suchand such traits of an animal we may calculate those which are coexistent with themand those which are incompatible. (Cuvier, 1817, vol. 1, p. 10; quoted in Coleman,1964, p. 77)

Thus, for instance, if an organism has a backbone—if it is a vertebrate—thenone knows at once that it must have an internal structure of a particular kind (Fig.1). It would not be compatible with a backbone to have (say) a digestive systemor circulatory system which we find characteristic of insects or arachnids. Then,if one has a vertebrate with a stomach of a particular kind, let us say ruminant, thenone knows at once that this group cannot contain organisms which are carnivores. Itcan hold only those organisms which are suited for ruminant-type existence. Andso on and so forth until one comes down to the individual organism. Workingoutwards from this principle, Cuvier argued that there are four major divisions orembranchements: the vertebrates, molluscs, articulata (insects, spiders, and soforth), and radiata.

A crucial consequence of the Cuverian organic world picture is that evolutionis not simply empirically false, but at some deeper conceptual level totally imposs-ible (Ruse 1979, 1996). If organisms are tightly organized teleologically, then thevery possibility of a passage from one form to another is precluded, virtually bydefinition. Transitional forms would be teleologically suited neither for the parentway of life, nor for the offspring way of life. Their parts would fail to serve in anintegrated fashion the end of the organisms’ overall well-being. It is therefore forthis reason that not only does one not find transitional forms between theembranch-ementsin real life, but that one knows that such a search is doomed to failure.


Fig. 1. Drawings of (a) a quadruped bent over backwards and (b) a cuttlefish. FromCuvier (1830, p. 179).

There can be no links between classes, and hence there can be no evolutionarytransitions down through the ages.

Cuverian teleology was the mainstay of much biology in the half century ormore before 1859, the year in which Darwin published his evolutionary ideas inthe Origin of Species. It was taken up and elaborated by biologists both withinFrance and abroad, particularly in Britain where Cuvier’s ideas were rapidlyabsorbed and promoted. It was also taken up by theoreticians of science. The end-focused way of thought that is inherent in the conditions-of-existence principlefitted naturally and smoothly with much of the philosophical and theological analy-ses which were then being developed and promoted. In Britain, in particular, thiswas the heyday of natural theology: most significant and trumpeted was the argu-ment from design (for God’s existence), the so-called teleological argument. Thesupposed design-like nature of organisms was taken as direct and immediate proofof the existence of an Artificer in the Sky: the Christian Deity (Paley, 1819).

One finds that important commentator on the sciences, William Whewell, devot-ing much attention in hisHistory of the Inductive Sciences(Whewell, 1837) toCuvier and his conclusions. Then, in thePhilosophy of the Inductive Sciences(1840) Whewell makes a Cuverian form of teleology absolutely central to analysesof organisms. In particular, Whewell subsumes teleology under what he calls the‘Fundamental Idea of Final Cause’.

Stones slide from a rock down the side of a hill and cause it to be smooth; thesmoothness of the slope causes stones still to slide. Yet no one would call such a


slide an organized system. The system is organized, when the effects which take placeamong the parts areessential to our conception of the whole; when the whole wouldnot be a whole, nor the parts, parts, except these effects were produced; when theeffects not only happen in fact, but are included in the idea of the object; when theyare not only seen, but foreseen; not only expected, but intended: in short when, insteadof being causes and effects, they areendsandmeans, as they are termed... Thus wenecessarily include, in our Idea of Organization, the notion of an end, a purpose, adesign; or, to use another phrase which has been peculiarly appropriated in this case,a Final Cause. This idea of a Final Cause is an essential condition in order to thepursuing our researches respecting organized bodies. (Whewell, 1840, vol. 2, p. 78)

Naturally enough, Whewell was happy to follow Cuvier not only in his biologicalthinking, but also in his conclusions that evolution is not only empirically false, butin a deeper sense conceptually impossible (Ruse, 1977). This comes out particularlystrongly in his (Whewell, 1845) responses to the anonymous evolutionary tractVestiges of the Natural History of Creation(published in 1844 and now known tohave been authored by the Scottish publisher Robert Chambers (1844)).

One should say, and this is important for our subsequent story, that Cuvier andhis followers did not have things entirely their way. There were those who deniedthat organisms are as tightly fitted to their environments, and as well-coordinatedinternally, as a Cuverian approach to nature would imply. More importantly, therewere those who argued that the whole emphasis on functional teleology detractsfrom important, perhaps even more important, alternative aspects of the livingworld. In particular, in Germany the so-calledNaturphilosophen—the transcen-dental morphologists—stressed that, in addition to direct functionality, organismsshow striking aspects which have no immediate ends (Richards, 1992). In this theywere paralleled in France by Cuvier’s great anatomical rival, Geoffroy Saint-Hilaire(1818). Then later in England, they were followed by the anatomist Richard Owen(1849), for all that he was often known as the ‘British Cuvier’. These thinkerspointed to the isomorphisms—now (following Owen) known as ‘homologies’—which exist between organisms, often of very different overall structure and habitatand behaviour.

Most famously there are the isomorphisms or homologies existing between theforelimbs of vertebrates of very different kinds (Fig. 2). The bones of the forelimbcan be put in one–one correspondence: between the human, who uses the forelimbfor grasping; the horse, who uses the forelimb for running; the bat, who uses theforelimb for flying; the bird, who likewise uses the forelimb for flying; the mole,who uses the forelimb for digging; and the whale, who uses the forelimb for swim-ming. All very different ends, and yet with isomorphisms between the bones. (Thecomplete isomorphism is often not possible, since some bones are missing in someorganisms, but there is an essential correspondence.)

It is obvious that these isomorphisms or homologies serve no immediate ends.They were therefore explained in terms of underlying structures which existthroughout nature, perhaps indeed connecting the living with the inanimate. Most


Fig. 2. Homologies between the forelimbs of several vertebrates. Numbers refer to digits.From Dobzhanskyet al. (1977, p. 264). Copyright 1977 by W. H. Freeman and Company.

Used with permission.

importantly, the more extreme thinkers of this kind were eager to show that thesimilarities exist not only within the Cuverian categories but perhaps even bridgethe most basic of them all, that is to say theembranchements. Notoriously, Geof-froy crossed swords with Cuvier over the possible homologies existing between


vertebrates and invertebrates (Appel, 1987). It hardly needs saying that, if indeedthe Cuverian categories can be breached and crossed over, then the conceptualfoundations of the argument against evolution are much weakened.

Although it is difficult to quantify these sorts of things, it seems clear that, bythe middle of the last century, the direct teleological approach and the challengingtranscendentalist approach were both seen as significant aspects of the living world.Perhaps it is fair to say that the tide was starting to run more strongly towardstranscendentalism. In the 1830s it is probably true to say—certainly in Britain, andperhaps also in France—that Cuverian teleology held sway. But by the 1850s, withCuvier now several decades gone, and with the rise of German academic biologicalscience, more and more stress was being put on comparative morphology and onthe task of tracing essential isomorphisms between organisms. Certainly, if onelooks at the work of a young morphologist like Thomas Henry Huxley (1898),who came to prominence in the 1850s, one finds that there is almost no attentionpaid to the older Cuverian teleology. But much stress is put on and significancegiven to the links between different organic forms as manifested by their homologi-cal similarities. It is at this point that Darwin enters the scene, publicly, with theOrigin of Species(1859).

2. Darwinian Evolutionism

Charles Darwin is rightly called the ‘father’ of evolution (Browne, 1995). Hisgreat book, theOrigin of Species, establishes the fact of evolution once and forall. Drawing on a wide range of organic phenomena—instinct, paleontology, bioge-ography, morphology, embryology, systematics, and more—Darwin showed thatif one supposes a common origin for all organisms living and dead, then one canexplain many facts hitherto inexplicable (Fig. 3). Conversely, these facts prove thetruth of the overall hypothesis of evolution. Thus, for instance, Darwin drew atten-tion to the ways in which the denizens of oceanic island clusters are often verysimilar to each other, yet slightly different. He explained these similarities anddifferences in terms of common descent. Likewise, Darwin drew attention to theroughly progressive nature of the fossil record, explaining this in terms of descentwith modification. And, turning to embryology, Darwin was happy to point to thesimilarities between the embryos of organisms widely different as adults—the dogand the human, for instance—pointing yet again to the fact that their ancestorswere one and the same.

The fact of evolution gives an immediate explanation of organic isomorphismsor homologies. This is what Darwin, like others, referred to as the ‘unity of type’.‘By unity of type is meant that fundamental agreement in structure, which we seein organic beings of the same class, and which is quite independent of their habitsof life. On my theory, unity of type is explained by unity of descent’ (Darwin,1859, p. 233). Had Darwin been Thomas Henry Huxley, this would probably havebeen the end of the matter. The essential aspects of organic nature, homologies,


Fig. 3. The structure of Darwin’s argument for the fact of evolution. The fact explainsand unifies claims made in the subdisciplines (only some of which are shown) which in turn

yield the ‘circumstantial evidence’ for the fact itself.

would now have been explained through evolution. The way would now beopened—an opening through which Huxley and his fellow morphologists marchedin the 1860s and 1870s—to look at the details of organic construction and to makeinferences about the paths of evolution (‘phylogenies’). There would have beenlittle or no reason to push one’s inquiries further.

Darwin, however, for all that he published in the late 1850s and had by thenmade himself a master of comparative morphology through his detailed studies ofbarnacles, was truly a child of the 1830s: the time when he formulated his basicideas about evolution. Darwin—a man educated at the University of Cambridge(the home of the great Isaac Newton) and a prote´ge of such important thinkers asWilliam Whewell—always took seriously the task of providing a causal expla-nation in science. Indeed, no doubt hoping to be the Newton of biology, afterbecoming an evolutionist Darwin searched hard for some causal mechanism akinto a Newtonian gravitational force. As is well known, Darwin eventually foundthis mechanism late in 1838: natural selection following on from the Malthusianpopulation explosion which is always occurring amongst animals and plants.

First, Darwin argued that there will necessarily be a struggle for existence:

A struggle for existence inevitably follows from the high rate at which all organicbeings tend to increase. Every being, which during its natural lifetime produces sev-


eral eggs or seeds, must suffer destruction during some period of its life, and duringsome season or occasional year, otherwise on the principle of geometrical increase,its numbers would quickly become so inordinately great that no country could supportthe product. Hence, as more individuals are produced than can possibly survive, theremust in every case be a struggle for existence, either one individual with another ofthe same species, or with the individuals of distinct species, or with the physicalconditions of life. It is the doctrine of Malthus applied with manifold force to thewhole animal and vegetable kingdoms; for in this case there can be no artificialincrease of food, and no prudential restraint from marriage. (Darwin, 1859, p. 63)

Then, noting that populations of organisms inevitably contain variation, Darwinargued that success in the struggle will be a function of the particular distinctivecharacteristics owned by the winners. Hence, there will be a natural form of selec-tion or winnowing:

Can the principle of selection, which we have seen is so potent in the hands of man,apply in nature? I think we shall see that it can act most effectually... Can it...bethought improbable, seeing that variations useful to man have undoubtedly occurred,that other variations useful in some way to each being in the great and complex battleof life, should sometimes occur in the course of thousands of generations? If suchdo occur, can we doubt (remembering that many more individuals are born than canpossibly survive) that individuals having any advantage, however slight, over others,would have the best chance of surviving and of procreating their kind? On the otherhand, we may feel sure that any variation in the least degree injurious would berigidly destroyed. This preservation of favourable variations and rejection of injuriousvariations, I call Natural Selection. (Darwin, 1859, pp. 80–1)

The important thing to note about Darwin’s mechanism of natural selection isthat not only is it a mechanism which leads to evolutionary change, and hence notonly is it a mechanism which leads to an explanation of the unity of type, but itspeaks also to organic design or functionality: that very aspect of organic naturehighlighted by Cuvier through his doctrine of the conditions of existence. Darwinis explicit on this matter: natural selection promotes ‘adaptations’ like the eye andthe hand and all other such characteristics. Darwin stresses that one must go beyondevolution and the unity of type to selection and adaptation or Cuverian teleology.Picking up on a passage quoted earlier:

On my theory, unity of type is explained by unity of descent. The expression ofconditions of existence, so often insisted on by the illustrious Cuvier, is fullyembraced by the principle of natural selection. For natural selection acts by eithernow adapting the varying parts of each being to its organic and inorganic conditionsof life; or by having adapted them during long-past periods of time: the adaptationsbeing aided in some cases by use and disuse, being slightly affected by the directaction of the external conditions of life, and being in all cases subjected to the severallaws of growth. Hence, in fact, the law of the Conditions of Existence is the higherlaw; as it includes, through the inheritance of former adaptations, that of Unity ofType. (Darwin, 1859, p. 233)


It can be seen here indeed that the unity of type for Darwin, although important,is subsidiary to the conditions of existence or teleology. Although now publishingin 1859, Darwin was forcing biological thought back twenty years to the time whenhe conceived his theory. Even though Darwin’s great supporters like Huxley wererelatively indifferent to Cuverian teleology and to adaptation, Darwin himselfstressed its significance. In this, one might therefore say that, whatever Darwin’stheological and other commitments, he was completely committed to the teleolog-ists’ initial premise: organisms are design-like, whatever the ultimate cause of thisdesign. (By the time of theOrigin, Darwin had moved from Christian theism toa form of deism. He probably did therefore believe in a Creator who designed,albeit a Creator who executes design through unbroken law, rather than throughdirect miraculous interference. Later in life, Darwin’s deism faded into a form ofagnosticism. This was partly due to the influence of Huxley and partly due toDarwin’s inability to reconcile any kind of god with the pain and evil in the world.)

As is well known, from the time of theOrigin down to the present the mech-anism of natural selection has had a somewhat checkered and varied existence(Bowler, 1984). For many years, selection was dismissed as an insignificant forcein nature. Although some made much of selection, notably Alfred Russel Wallace(1905), the co-discoverer of the mechanism, and his close friend Henry WalterBates (1892), general opinion was much influenced by Huxley and his group, rele-gating selection to a minor or even miniscule role. It was thought unnecessary andin any case deemed ineffective. This more or less continued to be the case, withsome notable exceptions (for instance the ardent Oxford evolutionists Raphael Wel-don and Edward Poulton), until the 1930s. Then selection came into its own, thanksfirst to the work of the genetical mathematical theorists R. A. Fisher, J. B. S.Haldane and Sewall Wright, and then second to the empiricists like the Russian-born American geneticist Theodosius Dobzhansky, and the British entomologistand ecologist E. B. Ford (Ruse, 1996).

A hundred years after theOrigin, at the time of the centenary in 1959, selectionseemed fully secure: the major mechanism of evolutionary change. And in respectsit has retained this status, especially in those quarters interested in such issues associal behaviour. Thanks to the work of theoretical sociobiologists such as WilliamHamilton (1964a,b) and John Maynard Smith (1982), and their empiricist followerssuch as Nicholas Davies (1992) and Geoffrey Parker (1978), natural selection con-tinues today to be an absolutely crucial tool in dissecting evolutionary aspects of theorganic world. However, notoriously, in the past two or three decades considerableopposition has again started to rise against selection. This attack is spearheadedparticularly by American paleontologists and geneticists, notably Stephen JayGould and Richard C. Lewontin (1978). It is claimed that selection is much over-praised, and that perhaps we ought to revert more to a Germanic-type understandingof evolution: an understanding where the unity of type again takes precedence overthe conditions of existence. The key term here is that of ‘Bauplan,’ a German term


meaning groundplan or blueprint: what pre-Darwinian English evolutionists usedto call the ‘archetype’, meaning the non-adaptive structure on which the organismwas based and from which all homologous parts are modeled.

In continental Europe, evolutionists have never been much attracted to the Anglo-American penchant for atomizing organisms into parts and trying to explain each asa direct adaptation. Their general alternative... acknowledges conventional selectionfor superficial modifications of theBauplan. It also denies that the adaptationist pro-gramme (atomization plus optimizing selection on parts) can do much to explainBauplane and the transitions between them. But it does not therefore resort to afundamentally unknown process. It holds that the basic body plans of organisms areso integrated and so replete with constraints upon adaptation... that conventional stylesof selective arguments can explain little of interest about them. It does not deny thatchange, when it occurs, may be mediated by natural selection, but it holds that con-straints restrict possible paths and modes of change so strongly that the constraintsthemselves become much the most interesting aspect of evolution. (Gould and Lewon-tin, 1979, p. 265).

Putting matters in the terms of our discussion, we can say simply that theimportant issue for Darwin, and for evolutionists from Darwin down to the present,has been that of organic teleology. Those evolutionary biologists who agree withDarwin (and with Cuvier before him) think that the distinctive mark of the organicworld is its forward-looking functionality. Organisms are adapted, hence they areteleological, and (for the Darwinian) this teleology can be explained through, andonly through, natural selection. Consider the writings of today’s most ardent Dar-winian: Richard Dawkins. He argues thatthe mark of the living is its teleologicalnature, and that such teleology can be explained only through natural selection.No other mechanism will do.

The key to the Darwinian explanation of adaptive complexity is the replacement ofinstantaneous, coincidental, multi-dimensional luck, by gradual, inch by inch, sme-ared-out luck. Luck is involved, to be sure. But a theory that bunches the luck upinto major steps is more incredible than a theory that spreads the luck out in smallstages. This leads to the following general principle of universal biology. Whereverin the universe adaptive complexity shall be found, it will have come into beinggradually through a series of small alterations, never through large and suddenincrements in adaptive complexity. (Dawkins, 1983, p. 412)

All the putative evolutionary rivals to natural selection which address adaptation—notably the venerable belief in the inheritance of acquired characteristics, so call‘Lamarckism’—are known to be false. So it is natural selection or nothing.

My general point is that there is one limiting constraint upon all speculations aboutlife in the universe. If a life-form displays adaptive complexity, it must possess anevolutionary mechanism capable of generating adaptive complexity. However diverseevolutionary mechanisms may be, if there is no other generalization that can be made


about life all around the Universe, I am betting that it will always be recognizableas Darwinian life. The Darwinian Law... may be as universal as the great laws ofphysics. (Dawkins, 1983, p. 423)

On the other hand, those biologists—notably Gould and Lewontin—who denythat selection has such a major role to play are precisely those who fail to seeCuverian teleology writ large through the organic world. As we saw, these arebiologists under the influence of a kind of neo-Naturphilosophie: they see hom-ologies and their underlying patterns (so-calledBauplane) as the distinctive featureof the organic world.

In this discussion, it is perhaps not for me to judge whether today’s Darwinianshave the better of the argument over the critics. I am an ardent partisan in thecamp of Darwinism, seeing teleology and design nigh everywhere (Ruse, 1982). Imake even Cuvier look weak-kneed! Hence, I will simply conclude this sectionby stressing that, for the Darwinian, Cuverian-type teleology is an absolutely cru-cial fact of the organic world and one deeply in need of explanation. Such expla-nation comes through and probably only through natural selection. For the critics,Cuverian teleology is nowhere near as wide-spread and significant as its enthusiastsclaim. For them, therefore, although selection undoubtedly plays some role in theevolutionary origins of organic nature, it would be a grave mistake to overemphas-ize the significance of this role. There are other factors are work. Perhaps, sincethe overriding characteristic of organic nature is homology, it is enough to stressthe fact of evolution. Actual causes are less significant, and may indeed be littlemore than randomness or chance, rather than something of a consistent, directednature.

3. Looking Forward

We come now to our final question—What is the true nature and status of bio-logical teleology?—and we ask this question with an eye to teleology’s future roleand prospects in evolutionary thought. Let me start by acknowledging that thereare many who regret evolutionary biology’s teleological cast. They think that, eventhough natural selection may well have a role to play in biological thought, tele-ology itself is an unfortunate relic of pre-evolutionary Christian thought, or worse.(For some peculiar reason, in the eyes of many biologists, ‘worse’ usually refersto Greek thinkers, notably Plato and Aristotle. I will not stop here to dig moredeeply into the sources of this very strange illusion.)

Typical of teleology’s naysayers is the following editorial in a popular biologi-cal journal

Some writers seem to regard the use of teleological terminology such as ‘striving toattain goals’ as a way of catching the reader’s attention. Others apparently use itmetaphorically as a convenient method of examining problems. However, it is danger-ous because it results in careless thinking and writing, and it misleads readers not


trained in science who often mistake the metaphor for the truth. A humanist acquaint-ance... suggested a warning that ‘The attribution of purpose to plants is not intendedliterally, and if so taken is dangerous to your mental health’. Scientists can have goalsand can develop research strategies to attain them, but plants cannot, unless we arewilling to grant that they have intelligence and can make decisions. Terms such as‘strategy’ and ‘tactics’ are philosophically objectionable when applied to plants andlower animals, and are best left to politicians, the military, and athletic coaches.(Kramer, 1984, in Ruse, 1988, p. 186)

But is it going to be quite as easy to eliminate teleology as this writer supposes?And even if such teleology could be eliminated, would this be entirely a goodthing? Probably the answer to this question depends in major part on how muchwould be involved in the job of elimination. If it could be done readily and withouttoo much disruption, then why not remove it? And, in pursuit of such a goal, let menote that many philosophers have thought that the task of removal was reasonablystraightforward. Much impressed by the development of homing or goal-directeddevices in the Second World War—the rocket or submarine or missile which couldrespond to a moving target and redirect itself accordingly—in the 1950s and the1960s, it was popularly thought that here we have the key to an understanding andpossible removal of evolutionary teleology. The noted logical empiricist ErnestNagel (1961) argued that whenever biologists speak in terms of functions, or pur-poses, or ends or design, they are referring silently to systems which are goal-directed, or (as he put it) ‘directively organized’. This and this alone is the importand content of biological teleology. Thus, if one is prepared to acknowledge thatorganisms are goal-directed, and if one is perhaps prepared also to spell out theways in which such goal-directedness operates, the elimination of teleology fromevolutionary biology should be a fairly straightforward matter.

However, these optimistic suggestions and proposals have since been shown tobe less than entirely convincing. As was pointed out by the late C. H. Waddington(1957), people such as Nagel are confusing two similar-sounding, but somewhatdifferent, biological notions: ‘adaptability’ and ‘adaptedness’. To say that an organ-ism is ‘adaptable’ is to say truly that it is goal-directed or directively organized ina Nagelian sense. It is to say that, if something occurs, the organism can in someway bring itself back on track. A paradigm instance is shivering and sweating inthe mammal: activities which are designed to return an overheated or overcooledorganism to its desired, constant, internal temperature. But, note that to say thatan organism is ‘adaptable’ is not in itself to say that an organism is ‘adapted’, orconversely. It is undoubtedly true that just about every organism is going to beadaptable in some sense or another, and also any successful organism must beadapted. However, if an organism is well-adapted, in this particular respect it maywell have no scope for response at all. To say, for instance, that because of itswhite fur coat the polar bear is well-adapted to an arctic life, is not in any senseto say that, should global warming eliminate most of the arctic ice and snow, thepolar bear could then immediately respond by turning brown or some other more


useful colour. It could well be that polar bears would go extinct, because they wereunable to change. Adaptedness does not spell adaptability, and conversely, one canreadily think of instances where something may well be adaptable, in the sense ofable to respond to change, and yet the organism would be in a better state if it wereto stick things out through minor environmental fluctuations without changing.

Unfortunately for the biology-teleology-eliminators, as we have seen, the tele-ology of biology—focused as it is on natural selection—refers to adaptedness notto adaptabililty. To say that the polar bear’s coat colour serves the end of survivaland reproduction of its owner—that the whiteness exists in order to promote polarbear well-being—is to say that the coat colour is an adaptation. In addition, it isto point out that polar bears were in some sense selected for their habitat: thatthose who were less than white failed to survive and reproduce as efficiently asthose who were. Nothing here is being said about adaptability. Hence, one has toconclude that, although indeed polar bears are probably adaptable, inasmuch asone is thinking of them teleologically, one is not referring to this particular aspectof their nature.

One is returned then to the whole question of adaptiveness. And let us note thatwhat we have here is a metaphor: organisms are being treated as if they weredesigned (Ruse, 1989). One might in fact think that they are designed, by the GreatDesigner in the Sky. But the point here is that, whether or not God stands behindthe design-like nature of organisms, inasmuch as one is doing biology one is simplytreating organisms as if they were designed. To use another memorable metaphor,namely that of Richard Dawkins (1986),quabiologist one is assuming that a ‘blindwatchmaker’ has been at work rather than a conscious intelligence. The metaphorin play here is that of a human-constructed artifact or object. A pair of scissors,for instance, is designed by humans: it has an intentionality and teleology, becausewe confer such intentionality upon it. The scissors exist in order to cut, becausethat is our desire. The forward-looking nature of scissors comes, not from causesoperating out of the future or anything like that, or even in a sense from somethinginherently in the scissors themselves, but rather from human intentions. Intentionswhich we have now, but which refer to events which we hope will obtain in thefuture. (As a number of people have pointed out, it is important to stress that thehope is that the events will obtain in the future, not that they will obtain. Otherwiseone gets caught with the so-called ‘missing goal object problem’, where one isassuming that things are being affected by future events which may not occur. Thescissors may never be used for cutting, because they get lost shortly after purchase.)

The whole point about organisms is that, inasmuch as we are thinking of themteleologically, we are thinking of them as objects of design. This is the reason whyteleological language seems appropriate in the organic world, but not elsewhere.Rocks and planets and moons and the like just simply do not seem as if designed.However, the fins on the back of the Stegosaurus do seem as if they were con-sciously planned (Fig. 4). As biologists have pointed out, they are very similar to


Fig. 4. Stegosaurus, a large herbivorous dinosaur of the Jurassic period, had an array ofbony plates along its back. Were they a solution to the problems of defence, courtshiprecognition or heat regulation? An engineering analysis reveals features characteristic ofheat regulation: porous structure (suggesting a rich blood supply), particularly large platesover the massive part of the body, staggered arrangement along the midline, a constrictionnear the base, and so on. This skeleton in the American Museum of Natural History is5.5 m long. From Lewontin (1978, p. 217). Reprinted with the permission of the estate of

Bunji Tegawa.

the fins that one finds on heat-exchange mechanisms surrounding electrical gener-ators. For this reason one is happy to talk about the function, or end, or purposeof the Stegosaurus’ back adornments. As in generators, the fins exist in order topromote heat exchange. They are like human artifacts and so, as in the case ofreal artifacts, teleological language is appropriate. Likewise, to use my own favour-ite example, the eyes of the trilobite (Fig. 5) are made with two lenses to correctfor chromatic aberration, just as Descartes and Huygens worked out (Fig. 6) somefive hundred million years after those particular invertebrates flourished (Clarksonand Levi-Setti, 1975).

Having stressed the fact that we have here a metaphor, is this not also the clueas to why now such teleology might at least in principle be eliminable? Manywould argue that, although metaphors do indeed occur frequently in science, insome important sense they are dispensable: indeed, the mark of a mature scienceis that metaphors can be and are so eliminated. As Jerry Fodor (1996) has said,when science gets serious metaphors go out and mathematics comes in.

I suspect that, if one were so determined, in principle one could eliminate themetaphors of science. At least, let me speak in a more restricted way and say that,if one were determined, I suspect that one could in principle eliminate the metaphorof design from evolutionary biology. One could have an evolutionary biologywhich spoke not at all in teleological language. At the most drastic, one wouldsimply refuse to consider questions of functionality at all. One would concentrate—in a kind of exaggerated parody of Gould and Lewontin—exclusively on such


Fig. 5. Trilobites are long-extinct marine invertebrates whose ecological niche is todaytaken by crabs and like creatures. They had very complex eyes using a large number oflenses. This is a much magnified photograph of such a trilobite eye. From Clarkson and

Levi-Setti (1975, p. 663). Reprinted with permission of the authors. Copyright Nature.

issues as homology and the consequent unity of type. (In real life, I agree thatGould and Lewontin do acknowledge some degree of adaptation.) Somewhat lessdrastically, I suspect that if one were determined, one could even look at adap-tations—the eye and the hand—and refuse to think teleologically. One couldcharacterize natural selection simply in terms of a differential reproduction, point-ing exclusively to what has happened in the past. Thus, in speaking of the fins ofthe Stegosaurus, one would ask not what purpose or function these fins play. Onewould simply talk in terms of past events. One would say that those Stegosauriwith more and more diamond-like-shaped fins were those that survived and repro-duced, and those which did not have such fins did not. One could even go on tosay precisely why it was that the successful Stegosauri survived and reproduced:the more diamond-like fins acted as efficient heat transfers, whereas those lessdiamond shaped acted as less efficient heat transfers. There was a consequent differ-ential reproduction of the respective possessors. And the same is true of otherorganisms, like the trilobites.

But note, even here, how limited or truncated one’s thinking is. One is able toprovide the non-teleological explanation about heat transference only because oneknows this to be the answer already! The question I ask—the question that evol-utionary biologists ask—is how did one know in the first place that the fins would


Fig. 6. How does one design a lens which avoids spherical aberration? In the seventeenthcentury, Rene´ Descartes (upper left) and Christian Huygens (upper right) discovered theshape of the required lenses. However, as the lower diagrams (cross-sections of two trilobiteeyes) show, nature had beaten them by a long time. The trilobite intralensar bowls areneeded for sharp focusing because trilobite eyes functioned in water. From Clarkson and

Levi-Setti (1975, p. 665) Reprinted with permission of the authors. Copyright Nature.

or would not be efficient for heat transference? The answer of course is becauseone has being relying on the metaphor of design! Precisely because one has beingthinking of the Stegosaurus’ parts as artifacts, that is to say as objects of consciousintention, one has been able to ferret out in which ways they work. In which waysthey work as objects of intention. Precisely because one is thinking of the trilobiteeye lenses as if designed and created by a real optician, can one find out why theyare as they are and how they worked. One might now drop the metaphor-like talk,but remember one has had it and relied on it in the first place. One is not doingwithout it: one is simply not acknowledging it.

My point therefore is that this kind of elimination of teleology is all a little bitbogus. One is using a sleight of hand. First, one uses the metaphor with all of itsteleological implications. Then second, when once one has achieved the ends onedesires, one drops the metaphor like an unwanted spouse and one pretends thatone never had anything to do with it all. The children of the union are there forone to claim for one’s own, and the former partner is locked out entirely. But


although one might be able to get away with this socially (less so these days ofcourse), intellectually, in the scientific realm, this is illicit. At best shady practicein the cause of a dubious philosophical thesis. Even one’s finished formal theorymakes no direct reference to the metaphor of design, and thus eliminates the tele-ology, even though in order to achieve the end results one has had to use themetaphor with all of the teleological implications that it carries. No one is goingto be able to say why those Stegosaurus fins exist and in what form without themetaphor.

Note what is going on here. The metaphor of design is being used as an essentialheuristic guide in evolutionary biology: precisely the role that students of metaphoralways attribute to such modes of thinking (Ruse, 1999). Whether or not metaphorsare an essential part of theories, they are absolutely essential for the productionof such theories (Hesse, 1966). Inasmuch as one’s scientific theory—in our caseevolutionary biology—is heuristically powerful, or in other language has the epis-temic virtue of fertility, one is relying heavily on metaphor—in our case, the meta-phor of design. Because, and only because, evolutionary biologists think of organ-isms as if they were humanly-made artifacts can they produce answers to questionsabout the ways in which these organisms survive and reproduce; that is to say, canthey produce answers about the ways in which natural selection functions in theorganic world.

Of course, you may want to argue that functionality has been overdone in evol-utionary biology. This is a matter which has been discussed already in this paper,and is one that I have laid on one side. For myself, as with other Darwinians, Iregard functionality to be the absolutely central feature of life. Even if one deniesthis centrality, one must still agree that functionality has some role to play in ourunderstanding of organic life and of its change. Even critics like Gould and Lewon-tin admit this much. Hence, I would argue that because such functionality is animportant aspect of organic nature and because it is produced by natural selection,the metaphor of design is here to stay and should be recognized fully for what itis. In other words, what I argue is that, however wrong Cuvier may have beenabout teleology precluding evolution, he was surely right in arguing that an essen-tial aspect of organic nature is its forward-looking cast. I have never been entirelyconvinced by Foucault’s clever claim that evolutionary biology owes more to Cuv-ier than to Lamarck, but there is surely some truth in it (Foucault, 1970).

4. Conclusion

Biological teleology is something which predates evolutionary thought. It wastaken over by evolutionists, particularly by Charles Darwin in hisOrigin of Speciesbecause the problems it addressed exist as much for the evolutionist as they dofor the nonevolutionist. In particular, organisms seem as if designed; they areadapted, and this calls for explanation. It is for this reason that teleological thoughtis appropriate in the biological sciences; and because nonorganisms do not seem


as if designed, teleological thought is inappropriate in the nonbiological, physicalsciences. Post-Darwin, teleological thought is intimately connected with naturalselection, and this explains why even today there is a divide between evolutionistson the matter of teleology. Those who follow Darwin think that adaptation is ofcrucial importance: therefore, they champion natural selection, and cherish teleo-logical thinking. Those who do not follow Darwin deny the great significance ofadaptation: they are less enthused by natural selection and they are less enamoredby teleological thought.

Philosophically speaking, perhaps in principle teleology can be eliminated frombiological thought, even from evolutionary biological thought. But to do so wouldbe to cut off interesting and surely important areas of inquiry. Teleology dependson a metaphor and as with all scientific metaphors this is the secret to science’sheuristic power, to its predictive fertility. It is for this reason that the teleology ofevolutionary biology is surely here to stay and might be expected to flourish inthe future. In a sense, therefore, although the coming of evolutionary biology,particularly the coming of Darwinian evolutionary biology, was the most importantthing ever to happen to the biological sciences, its particular significance lies inits giving new answers to old questions, rather than in always asking entirely newquestions. Teleology: yesterday, today, and tomorrow!

References

Appel, T. A. (1987)The Cuvier-Geoffroy Debate: French Biology in the Decades BeforeDarwin (New York: Oxford University Press).

Bates, H. W. (1892)The Naturalist on the River Amazon(London: John Murray; first pub-lished in 1863).

Bowler, P. (1984)Evolution: The History of an Idea(Berkeley: University of CaliforniaPress).

Browne, J. (1995)Charles Darwin: Voyaging. Volume 1 of a Biography(New York: Knopf).Chambers, R. (1844)Vestiges of the Natural History of Creation(London: Churchill).Clarkson, E. N. K. and Levi-Setti, R. (1975) ‘Trilobite Eyes and the Optics of Descartes

and Huygens’,Nature254, 663–67.Coleman, W. (1964)Georges Cuvier, Zoologist: A Study in the History of Evolution Theory

(Cambridge, MA: Harvard University Press).Cuvier, G. (1813)Essay on the Theory of the Earth, trans. R. Kerr (Edinburgh: W.

Blackwood).Cuvier, G. (1817)Le regne animal distribue´ d’apres son organisation, pour servir de base

a l’histoire naturelle des animaux et d’introduction a` l’anatomie compare´e (Paris:Deterville).

Cuvier, G. (1830) ‘Conside´rations sur les Mollusques, et en particulier sur les Ce´phalopo-des’, Annales des sciences naturelles19, 241–359.

Darwin, C. (1859)On the Origin of Species(London: John Murray).Davies, N. B. (1992)Dunnock Behaviour and Social Evolution(Oxford: Oxford Univer-

sity Press).Dawkins, R. (1983) ‘Universal Darwinism’, in D. S. Bendall (ed.)Molecules to Men

(Cambridge: Cambridge University Press) pp. 403–25.Dawkins, R. (1986)The Blind Watchmaker(New York: Norton).Dobzhansky, T., Ayala, F. J., Stebbins, G. L. and Valentine, J. W. (1977)Evolution (San

Francisco: W. H. Freeman).


Fodor, J. (1996) ‘Peacocking’,London Review of Books, 18 April, 19–20.Foucault, M. (1970)The Order of Things: An Archaeology of the Human Sciences(New

York: Pantheon).Geoffroy Saint-Hilaire, E. (1818)Philosophie anatomique(Paris: Mequignon-Marvis).Gould, S. J. and Lewontin, R. C. (1979) ‘The Spandrels of San Marco and the Panglossian

Paradigm: A Critique of the Adaptationist Programme’,Proceedings of the Royal Societyof London Series B: Biological Sciences205, 581–98.

Hamilton, W. D. (1964a) ‘The Genetical Evolution of Social Behaviour I’,Journal of Theor-etical Biology7, 1–16.

Hamilton, W. D. (1964b) ‘The Genetical Evolution of Social Behaviour II’,Journal ofTheoretical Biology7, 17–32.

Hesse, M. (1966)Models and Analogies in Science(Notre Dame: University of NotreDame Press).

Huxley, T. H. (1898)The Scientific Memoirs of Thomas Henry Huxley,4 vols, eds M. Fosterand E. R. Lankester (London: Macmillan).

Kramer, P. J. (1984) ‘Misuse of the Term “Strategy”’,BioScience34, 405.Lewontin, R. C. (1978) ‘Adaptation’,Scientific American239(3),223–30.Maynard Smith, J. (1982)Evolution and the Theory of Games(Cambridge: Cambridge Uni-

versity Press).Nagel, E. (1961)The Structure of Science: Problems in the Logic of Scientific Explanation

(New York: Harcourt, Brace and World).Nissen, L. (1997)Teleological Language in the Life Sciences(Lanham, MD: Rowman

and Littlefield).Owen, R. (1849)On the Nature of Limbs(London: Voorst).Paley, W. (1819)Natural Theology, vol. 4 of Paley’sCollected Works(London: Rivington,

first published in 1802).Parker, G. A. (1978) ‘Evolution of Competitive Mate Searching’,Annual Review of Ento-

mology23, 173–96.Richards, R. J. (1992)The Meaning of Evolution: The Morphological Construction and

Ideological Reconstruction of Darwin’s Theory(Chicago: University of Chicago Press).Ruse, M. (1977) ‘William Whewell and the Argument From Design’,Monist 60, 244–68.Rise, M. (1979)The Darwinian Revolution: Science Red in Tooth and Claw(Chicago:

University of Chicago Press).Ruse, M. (1982)Darwinism Defended: A Guide to Evolutionary Controversies(Reading,

MA: Benjamin/Cummings).Ruse, M. (ed) (1988)Readings in the Philosophy of Biology(New York: Macmillan).Ruse, M. (1989)The Darwinian Paradigm: Essays on its History, Philosophy and Religious

Implications(London: Routledge).Ruse, M. (1996)Monad to Man: The Concept of Progress in Evolutionary Biology

(Cambridge, Mass.: Harvard University Press).Ruse, M. (1999)Mystery of Mysteries: Is Evolution a Social Construction? (Cambridge,

MA: Harvard University Press).Waddington, C. H. (1957)The Strategy of the Genes(London: Allen and Unwin).Wallace, A. R. (1905)My Life: A Record of Events and Opinions(London: Chapman

and Hall).Whewell, W. (1837)The History of the Inductive Sciences, 3 vols, (London: Parker).Whewell, W. (1840)The Philosophy of the Inductive Sciences, 2 vols, (London: Parker).Whewell, W. (1845)Indications of the Creator(London: Parker).

teleology - yesterday, today, and tomorrow

Documents

harvard university

thomas henry

efcient heat

oxford university

darwin drew

cambridge

adaptive complexity

polar bear