Design without Designer - Darwin’s Greatest Discovery

The Copernican revolution consisted in a commitment to thepostulate that the universe is governed by natural laws that account for natu-ral phenomena.. The creative power of natural sele

4 Design without Designer

Darwin’s Greatest Discovery

Francisco J Ayala1

It is also frequently asked what our belief must be about the form and shape

of heaven according to Sacred Scripture Many scholars engage in lengthydiscussions on these matters. Such subjects are of no profit for those who

seek beatitude, and, what is worse, they take up very precious time that ought

to be given to what is spiritually beneficial What concern is it of mine whetherheaven is like a sphere and the earth is enclosed by it and suspended in themiddle of the universe? In the matter of the shape of heaven the sacred

writers did not wish to teach men these facts that would be of no avail for

their salvation

Saint Augustine, The Literal Meaning of Genesis, Book II, Chapter 92

New knowledge has led us to realize that the theory of evolution is no longer

a mere hypothesis It is indeed remarkable that this theory has been sively accepted by researchers, following a series of discoveries in various fields

progres-of knowledge The convergence, neither sought nor fabricated, progres-of the results

of work that was conducted independently is in itself a significant argument

in favor of this theory

Pope John Paul II, Address to the Pontifical Academy of Sciences,

October 22, 19963

synopsis

I advance three propositions and conclude with two additional arguments.The first proposition is that Darwin’s most significant intellectual contribu-tion is that he brought the origin and diversity of organisms into the realm

of science The Copernican revolution consisted in a commitment to thepostulate that the universe is governed by natural laws that account for natu-ral phenomena Darwin completed the Copernican revolution by extendingthat commitment to the living world

The second proposition is that natural selection is a creative process thatcan account for the appearance of genuine novelty How natural selection

55

creates is shown by using a simple example and then clarified using twoanalogies – artistic creation and the “typing monkeys” – with which it sharesimportant similarities and differences The creative power of natural selec-tion arises from a distinctive interaction between chance and necessity, orbetween random and deterministic processes.

The third proposition is that teleological explanations are necessary inorder to give a full account of the attributes of living organisms, whereasthey are neither necessary nor appropriate in the explanation of naturalinanimate phenomena I give a definition of “teleology” and clarify thematter by distinguishing between internal and external teleology, and be-tween bounded and unbounded teleology The human eye, so obviouslyconstituted for seeing but resulting from a natural process, is an example

of internal (or natural) teleology A knife has external (or artificial) ogy, because it has been purposefully designed by an external agent Thedevelopment of an egg into a chicken is an example of bounded (or nec-essary) teleology, whereas the evolutionary origin of the mammals is a case

teleol-of unbounded (or contingent) teleology, because there was nothing in themake-up of the first living cells that necessitated the eventual appearance ofmammals

An argument follows that the “design” of organisms is not “intelligent,”but rather quite incompatible with the design that we would expect of anintelligent designer or even of a human engineer, and so full of dysfunctions,wastes, and cruelties as to unwarrant its attribution to any being endowedwith superior intelligence, wisdom, and benevolence

My second argument simply asserts that as successful and encompassing

as science is as a way of knowing, it is not the only way

dar win’s revolution

The publication in 1859 of On the Origin of Species by Charles Darwin ushered

in a new era in the intellectual history of mankind Darwin is deservedlygiven credit for the theory of biological evolution: he accumulated evidencedemonstrating that organisms evolve and discovered the process – naturalselection – by which they evolve But the import of Darwin’s achievement isthat it completed the Copernican revolution initiated three centuries earlier,and that it thereby radically changed our conception of the universe andthe place of mankind in it

The discoveries of Copernicus, Kepler, Galileo, and Newton during thesixteenth and seventeenth centuries had gradually ushered in the notionthat the workings of the universe could be explained by human reason

It was shown that the Earth is not the center of the universe, but a smallplanet rotating around an average star; that the universe is immense inspace and in time; and that the motions of the planets around the sun can

be explained by the same simple laws that account for the motion of physical

objects on our planet These and other discoveries greatly expanded humanknowledge, but the intellectual revolution these scientists brought aboutwas more fundamental: a commitment to the postulate that the universeobeys immanent laws that account for natural phenomena The workings ofthe universe were brought into the realm of science: explanation throughnatural laws Physical phenomena could be accounted for whenever thecauses were adequately known.

Darwin completed the Copernican revolution by drawing out for biologythe notion of nature as a lawful system of matter in motion The adaptationsand diversity of organisms, the origin of novel and highly organized forms,even the origin of mankind itself – all could now be explained by an orderlyprocess of change governed by natural laws

The origin of organisms and their marvelous adaptations were, however,either left unexplained or attributed to the design of an omniscient Creator.God had created the birds and bees, the fish and corals, the trees in theforest, and, best of all, man God had given us eyes so that we might see, and

He had provided fish with gills with which to breathe in water Philosophersand theologians argued that the functional design of organisms manifeststhe existence of an all-wise Creator Wherever there is design, there is adesigner; the existence of a watch evinces the existence of a watchmaker

The English theologian William Paley, in his Natural Theology (1802),

elaborated the argument from design as a forceful demonstration of theexistence of the Creator The functional design of the human eye, arguedPaley, provided conclusive evidence of an all-wise Creator It would be absurd

to suppose, he wrote, that by mere chance the human eye “should haveconsisted, first, of a series of transparent lenses secondly of a black cloth

or canvas spread out behind these lenses so as to receive the image formed

by pencils of light transmitted through them, and placed at the precisegeometrical distance at which, and at which alone, a distinct image could beformed thirdly of a large nerve communicating between this membrane

and the brain.” The Bridgewater Treatises, published between 1833 and

1840, were written by eminent scientists and philosophers to set forth “thePower, Wisdom, and Goodness of God as manifested in the Creation.” Thestructure and mechanisms of the human hand, for example, were cited asincontrovertible evidence that the hand had been designed by the sameomniscient Power that had created the world.4

The advances of physical science had thus driven mankind’s conception

of the universe to a split-personality state of affairs, which persisted well intothe mid nineteenth century Scientific explanations, derived from naturallaws, dominated the world of nonliving matter, on the Earth as well as inthe heavens Supernatural explanations, depending on the unfathomabledeeds of the Creator, accounted for the origin and configuration of livingcreatures – the most diversified, complex, and interesting realities of theworld It was Darwin’s genius to resolve this conceptual schizophrenia

dar win’s discovery: design without designerThe conundrum faced by Darwin can hardly be overestimated The strength

of the argument from design for demonstrating the role of the Creator iseasily set forth Wherever there is function or design we look for its author Aknife is made for cutting, and a clock is made to tell time; their functional de-signs have been contrived by a knife maker and a watchmaker The exquisite

design of Leonardo da Vinci’s Mona Lisa proclaims that it was created by a

gifted artist following a preconceived plan Similarly, the structures, organs,and behaviors of living beings are directly organized to serve certain func-tions The functional design of organisms and their features would thereforeseem to argue for the existence of a designer It was Darwin’s greatest ac-complishment to show that the directive organization of living beings can

be explained as the result of a natural process – natural selection – withoutany need to resort to a Creator or other external agent The origin andadaptation of organisms in all of their profusion and wondrous variationwere thus brought into the realm of science

Darwin accepted that organisms are “designed” for certain purposes, that

is, that they are functionally organized Organisms are adapted to certainways of life, and their parts are adapted to perform certain functions Fishare adapted to live in water; kidneys are designed to regulate the compo-sition of blood; the human hand is made for grasping But Darwin went

on to provide a natural explanation of the design He thereby brought theseemingly purposeful aspects of living beings into the realm of science.Darwin’s revolutionary achievement is that he extended the Copernicanrevolution to the world of living things The origin and adaptive nature oforganisms could now be explained, like the phenomena of the inanimateworld, as the result of natural laws manifested in natural processes Darwin’stheory encountered opposition in some religious circles, not so much be-cause he proposed the evolutionary origin of living things (which had beenproposed before, and had been accepted even by Christian theologians),but because the causal mechanism – natural selection – excluded God asthe explanation for the obvious design of organisms.5 The configuration

of the universe was no longer perceived as the result of God’s design, butsimply as the outcome of immanent, blind processes There were, however,many theologians, philosophers, and scientists who saw no contradictionthen – and many who see none today – between the evolution of speciesand Christian faith Some see evolution as the “method of divine intelli-gence,” in the words of the nineteenth-century theologian A H Strong.Others, such as Henry Ward Beecher (1818–1887), an American contem-porary of Darwin, made evolution the cornerstone of their theology Thesetwo traditions have persisted to the present As cited at the beginning ofthis chapter, Pope John Paul II has stated that “the theory of evolution is nolonger a mere hypothesis It is accepted by researchers, following a series

of discoveries in various fields of knowledge.” “Process” theologians ceive evolutionary dynamics as a pervasive element of a Christian view of theworld.6

per-natural selection as a nonchance processThe central argument of the theory of natural selection is summarized by

Darwin in his Origin of Species as follows:

As more individuals are produced than can possibly survive, there must in everycase be a struggle for existence, either one individual with another of the samespecies, or with the individuals of distinct species, or with the physical conditions oflife. Can it, then, be thought improbable, seeing that variations useful to man have

undoubtedly occurred, that other variations useful in some way to each being in thegreat and complex battle of life, should sometimes occur in the course of thousands

of generations? If such do occur, can we doubt (remembering that more individualsare born than can possibly survive) that individuals having any advantage, howeverslight, over others, would have the best chance of surviving and of procreating theirkind? On the other hand, we may feel sure that any variation in the least degreeinjurious would be rigidly destroyed This preservation of favorable variation andthe rejection of injurious variations, I call Natural Selection.7

Darwin’s argument addresses the problem of explaining the adaptivecharacter of organisms Darwin argues that adaptive variations (“variationsuseful in some way to each being”) occasionally appear, and that these arelikely to increase the reproductive chances of their carriers Over the gen-erations, favorable variations will be preserved, and injurious ones will beeliminated In one place, Darwin adds: “I can see no limit to this power

[natural selection] in slowly and beautifully adapting each form to the most

complex relations of life.” Natural selection was proposed by Darwin ily in order to account for the adaptive organization, or “design,” of livingbeings; it is a process that promotes or maintains adaptation Evolution-ary change through time and evolutionary diversification (multiplication ofspecies) are not directly promoted by natural selection (hence the so-calledevolutionary stasis – the numerous examples of organisms with morphologythat has changed little, if at all, for millions of years, as pointed out by theproponents of the theory of punctuated equilibria) But change and diversi-fication often ensue as by-products of natural selection fostering adaptation.Darwin formulated natural selection primarily as differential survival Themodern understanding of the principle of natural selection is formulated ingenetic and statistical terms as differential reproduction Natural selectionimplies that, on the average, some genes and genetic combinations are trans-mitted to the following generations more frequently than their alternativegenetic units Such genetic units will become more common in every subse-quent generation, and the alternative units less common Natural selection

primar-is a statprimar-istical bias in the relative rate of reproduction of alternative geneticunits.

Natural selection has been compared to a sieve that retains the rarelyarising useful genes and lets go the more frequently arising harmful mutants.Natural selection acts in that way, but it is much more than a purely negativeprocess, for it is also able to generate novelty by increasing the probability ofotherwise extremely improbable genetic combinations Natural selection isthus in a way creative It does not “create” the entities upon which it operates,but it produces adaptive genetic combinations that would not have existedotherwise

The creative role of natural selection must not be understood in the sense

of the “absolute” creation that traditional Christian theology predicates ofthe Divine act by which the universe was brought into being ex nihilo Nat-ural selection may instead be compared to a painter who creates a picture

by mixing and distributing pigments in various ways over the canvas Thecanvas and the pigments are not created by the artist, but the painting is

It is conceivable that a random combination of the pigments might result

in the orderly whole that is the final work of art But the probability of

Leonardo’s Mona Lisa resulting from a random combination of pigments,

or of Saint Peter’s Basilica resulting from a random association of marble,bricks, and other materials, is infinitely small In the same way, the combi-nation of genetic units that carries the hereditary information responsiblefor the formation of the vertebrate eye could never have been produced by

a random process such as mutation – not even allowing for the more thanthree billion years during which life has existed on Earth The complicatedanatomy of the eye, like the exact functioning of the kidney, is the result of

a nonrandom process – natural selection

Critics have sometimes alleged as evidence against Darwin’s theory ofevolution examples showing that random processes cannot yield meaning-ful, organized outcomes It is thus pointed out that a series of monkeys

randomly striking letters on a typewriter would never write On the Origin

of Species, even if we allowed for millions of years and many generations of

monkeys pounding on typewriters

This criticism would be valid if evolution depended only on random cesses But natural selection is a nonrandom process that promotes adapta-tion by selecting combinations that “make sense” – that is, that are useful tothe organisms The analogy of the monkeys would be more appropriate if

pro-a process existed by which, first, mepro-aningful words would be chosen everytime they appeared on the typewriter; and then we would also have type-writers with previously selected words rather than just letters as the keys;and again there would be a process that selected meaningful sentencesevery time they appeared in this second typewriter If every time words such

as “the,” “origin,” “species,” and so on appeared in the first kind of writer, they each became a key in the second kind of typewriter, meaningful

type-sentences would occasionally be produced in this second typewriter If suchsentences became incorporated into the keys of a third kind of typewriter,

in which meaningful paragraphs were selected whenever they appeared, it

is clear that pages and even chapters “making sense” would eventually beproduced

We need not carry the analogy too far, since the analogy is not fullysatisfactory; but the point is clear Evolution is not the outcome of purelyrandom processes; rather, there is a “selecting” process, which picks upadaptive combinations because these reproduce more effectively and thusbecome established in populations These adaptive combinations constitute,

in turn, new levels of organization upon which the mutation (random) plusselection (nonrandom or directional) process again operates

The manner in which natural selection can generate novelty in the form

of accumulated hereditary information may be illustrated by the followingexample In order to be able to reproduce in a culture medium, some strains

of the colon bacterium Escherichia coli require that a certain substance, the

amino acid histidine, be provided in the medium When a few such teria are added to a cubic centimeter of liquid culture medium, they mul-tiply rapidly and produce between two and three billion bacteria in a fewhours Spontaneous mutations to streptomycin resistance occur in normal(i.e., sensitive) bacteria at rates of the order of one in one hundred million(1× 10−8) cells In our bacterial culture, we would expect between twenty

bac-and thirty bacteria to be resistant to streptomycin due to spontaneous tation If a proper concentration of the antibiotic is added to the culture,only the resistant cells survive The twenty or thirty surviving bacteria willstart reproducing, however, and – allowing a few hours for the necessarynumber of cell divisions – several billion bacteria will then be produced, allresistant to streptomycin Among cells requiring histidine as a growth factor,spontaneous mutations able to reproduce in the absence of histidine arise

mu-at a rmu-ate of about four in one hundred million (4× 10−8) bacteria The

streptomycin-resistant cells may now be transferred to a culture with tomycin but with no histidine Most of them will not be able to reproduce,but about a hundred will start reproducing until the available medium issaturated

strep-Natural selection has produced, in two steps, bacterial cells resistant tostreptomycin and not requiring histidine for growth The probability of thetwo mutational events happening in the same bacterium is of about four inten million billion (1× 10−8 × 4 × 10−8 = 4 × 10−16) cells An event of

such low probability is unlikely to occur even in a large laboratory culture ofbacterial cells With natural selection, cells having both properties are thecommon result

As illustrated by the bacterial example, natural selection produces nations of genes that would otherwise be highly improbable, because natu-ral selection proceeds stepwise The vertebrate eye did not appear suddenly

combi-in all its present perfection Its formation requires the appropriate combi-gration of many genetic units, and thus the eye could not have resultedfrom random processes alone For more than half a billion years, the an-cestors of today’s vertebrates had some kind of organ sensitive to light.Perception of light, and later vision, were important for these organisms’survival and reproductive success Accordingly, natural selection favoredgenes and gene combinations that increased the functional efficiency ofthe eye Such genetic units gradually accumulated, eventually leading tothe highly complex and efficient vertebrate eye Natural selection can ac-count for the rise and spread of genetic constitutions, and therefore of types

inte-of organisms, that would never have resulted from the uncontrolled action

of random mutation In this sense, natural selection is a creative process,although it does not create the raw materials – the genes – upon which

it acts.8

chance and necessityThere is an important respect in which artistic creation makes a poor anal-ogy to the process of natural selection A painter usually has a preconcep-tion of what he wants to paint and will consciously modify the painting

so that it represents what he wants Natural selection has no foresight,nor does it operate according to some preconceived plan Rather, it is apurely natural process resulting from the interacting properties of physico-chemical and biological entities Natural selection is simply a consequence

of the differential multiplication of living beings It has some appearance

of purposefulness, because it is conditioned by the environment: which ganisms reproduce more effectively depends on which variations they pos-sess that are useful in the organism’s environment But natural selectiondoes not anticipate the environments of the future; drastic environmentalchanges may be insuperable obstacles to organisms that were previouslythriving

or-The team of typing monkeys is also a bad analogy to evolution by naturalselection, because it assumes that there is “somebody” who selects lettercombinations and word combinations that make sense In evolution, there

is no one selecting adaptive combinations These select themselves, becausethey multiply more effectively than less adaptive ones

There is a sense in which the analogy of the typing monkeys is better thanthe analogy of the artist, at least if we assume that no particular statementwas to be obtained from the monkeys’ typing endeavors, just any statementmaking sense Natural selection strives to produce not predetermined kinds

of organisms, but only organisms that are adapted to their present ments Which characteristics will be selected depends on which variationshappen to be present at a given time and in a given place This, in turn,

environ-depends on the random process of mutation, as well as on the previoushistory of the organism (i.e., on its genetic make-up as a consequence ofprevious evolution) Natural selection is an “opportunistic” process Thevariables determining in which direction it will go are the environment,the preexisting constitution of the organisms, and the randomly arisingmutations.

Thus, adaptation to a given environment may occur in a variety of ent ways An example may be taken from the adaptations of plant life to adesert climate The fundamental adaptation is to the condition of dryness,which involves the danger of desiccation During a major part of the year –sometimes for several years in succession – there is no rain Plants have ac-complished the urgent necessity of saving water in different ways Cacti havetransformed their leaves into spines, having made their stems into barrelscontaining a reserve of water; photosynthesis is performed in the surface ofthe stem instead of in the leaves Other plants have no leaves during thedry season, but after it rains they burst into leaves and flowers and produceseeds Ephemeral plants germinate from seeds, grow, flower, and produceseeds all within the space of a few weeks, when rainwater is available; duringthe rest of the year the seeds lie quiescent in the soil

differ-The opportunistic character of natural selection is also well evidenced by

the phenomenon of adaptive radiation The evolution of Drosophila fruitflies

in Hawaii is a relatively recent adaptive radiation There are about 1,500

Drosophila species in the world Approximately 500 of them have evolved

in the Hawaiian archipelago, although this island group has a small area,about one twenty-fifth the size of California Moreover, the morphological,

ecological, and behavioral diversity of Hawaiian Drosophila exceeds that of

Drosophila in the rest of the world.

Why should have such “explosive” evolution have occurred in Hawaii?

The overabundance of Drosophila fruitflies there contrasts with the absence

of many other insects The ancestors of Hawaiian Drosophila reached the

archipelago before other groups of insects did, and thus they found a titude of unexploited opportunities for living They responded by a rapidadaptive radiation; although they are all probably derived from a single col-onizing species, they adapted to the diversity of opportunities available indiverse places and at different times by developing appropriate adaptations,which varied widely from one to another species

mul-The process of natural selection can explain the adaptive organization

of organisms, as well as their diversity and evolution as a consequence oftheir adaptation to the multifarious and ever-changing conditions of life.The fossil record shows that life has evolved in a haphazard fashion Theradiations, expansions, relays of one form by another, occasional but irreg-ular trends, and the ever-present extinctions are best explained by natu-ral selection of organisms subject to the vagaries of genetic mutation and

environmental challenge The scientific account of these events does notnecessitate recourse to a preordained plan, whether imprinted from with-out by an omniscient and all-powerful Designer, or resulting from someimmanent force driving the process towards definite outcomes Biologicalevolution differs from a painting or an artifact in that it is not the outcome

of a design preconceived by an artist or artisan

Natural selection accounts for the “design” of organisms, because tive variations tend to increase the probability of survival and reproduction

adap-of their carriers at the expense adap-of maladaptive, or less adaptive, variations.The arguments of Paley and the authors of the Bridgewater Treatises againstthe incredible improbability of chance accounts of the origin of organismsand their adaptations are well taken, as far as they go But neither thesescholars, nor any other writers before Darwin, were able to discern thatthere is a natural process (namely, natural selection) that is not random,but rather oriented and able to generate order, or to “create.”9 The traitsthat organisms acquire in their evolutionary histories are not fortuitousbut determined by their functional utility to the organisms, and they comeabout in small steps that accumulate over time, each step providing somereproductive advantage over the previous condition

Chance is, nevertheless, an integral part of the evolutionary process Themutations that yield the hereditary variations available to natural selectionarise at random, independent of whether they are beneficial or harmful

to their carriers But this random process (as well as others that come toplay in the great theater of life) is counteracted by natural selection, whichpreserves what is useful and eliminates the harmful Without mutation, evo-lution could not happen, because there would be no variations that could bedifferentially conveyed from one to another generation But without naturalselection, the mutation process would yield disorganization and extinction,because most mutations are disadvantageous Mutation and selection havejointly driven the marvelous process that, starting from microscopic organ-isms, has produced orchids, birds, and humans

The theory of evolution manifests chance and necessity jointly twined in the stuff of life; randomness and determinism interlocked in anatural process that has spurted the most complex, diverse, and beautifulentities in the universe: the organisms that populate the Earth, including hu-mans, who think and love, who are endowed with free will and creative pow-ers, and who are able to analyze the very process of evolution that broughtthem into existence This is Darwin’s fundamental discovery, that there is

inter-a process thinter-at is creinter-ative though not conscious And this is the conceptuinter-alrevolution that Darwin completed: that everything in nature, including theorigin of living organisms, can be accounted for as a result of natural pro-cesses governed by natural laws This is nothing if not a fundamental visionthat has forever changed how human beings perceive themselves and theirplace in the universe

teleology and teleological explanationsExplanation by design, or teleology, is, according to a dictionary defini-tion, “the use of design, purpose, or utility as an explanation of any naturalphenomenon.”10 An object or a behavior is said to be teleological when

it gives evidence of design or appears to be directed toward certain ends.For example, the behavior of human beings is often teleological A personwho buys an airplane ticket, reads a book, or cultivates the earth is trying toachieve a certain end: getting to a given city, acquiring knowledge, or gettingfood Objects and machines made by people are also usually teleological:

a knife is made for cutting; a clock is made for telling time; a thermostat

is made to regulate temperature Similarly, many features of organisms are

teleological: a bird’s wings are for flying; eyes are for seeing; kidneys are constituted for regulating the composition of the blood The features of or-

ganisms that may be said to be teleological are those that can be identified

as adaptations, whether they are structures such as a wing or a hand, organssuch as a kidney, or behaviors such as the courtship displays of a peacock.Adaptations are features of organisms that have come about by natural selec-tion because they serve certain functions and thus increase the reproductivesuccess of their carriers

Inanimate objects and processes (other than those created by people)are not teleological in the sense just explained, because we gain no addi-tional scientific understanding by perceiving them as directed toward spe-cific ends or as serving certain purposes The configuration of a sodiumchloride molecule (table salt) depends on the structure of sodium and chlo-rine, but it makes no sense to say that that structure is made in order to serve

a certain purpose, such as tasting salty Similarly, the shape of a mountain

is the result of certain geological processes, but it did not come about inorder to serve a certain purpose, such as providing slopes suitable for skiing.The motion of the Earth around the sun results from the laws of gravity, but

it does not exist in order that the seasons may occur We may use sodiumchloride as food, a mountain for skiing, and we may take advantage of theseasons, but the use that we make of these objects or phenomena is not thereason why they came into existence or why they have certain configurations

On the other hand, a knife and a car exist and have particular tions precisely in order to serve the purposes of cutting and transportation.Similarly, the wings of birds came about precisely because they permittedflying, which was reproductively advantageous The mating displays of pea-cocks came about because they increased the chances of mating and thus

configura-of leaving progeny

The previous comments point out the essential characteristics of logical phenomena, which may be encompassed in the following definition:

teleo-“Teleological explanations account for the existence of a certain feature in

a system by demonstrating the feature’s contribution to a specific property

of state of the system.” Teleological explanations require that the feature

or behavior contribute to the persistence of a certain state or property ofthe system: wings serve for flying; the sharpness of a knife serves for cutting.Moreover – and this is the essential component of the concept – this con-tribution must be the reason why the feature or behavior exists at all: thereason why wings came into existence is because they serve for flying; thereason why a knife is sharp is that it is intended for cutting

The configuration of a molecule of sodium chloride contributes to itsproperty of tasting salty and therefore to its use as food, not vice versa; thepotential use of sodium chloride as food is not the reason why it has a partic-ular molecular configuration or tastes salty The motion of the Earth aroundthe sun is the reason why seasons exist; the existence of the seasons is notthe reason why the Earth moves about the sun On the other hand, thesharpness of a knife can be explained teleologically, because the knife hasbeen created precisely to serve the purpose of cutting Motorcars and theirparticular configurations exist because they serve the purpose of transporta-tion, and thus can be explained teleologically Many features and behaviors

of organisms meet the requirements of teleological explanation.11The man hand, the wings of birds, the structure and behavior of kidneys, andthe mating displays of peacocks are examples already given.12

hu-It is useful to distinguish different kinds of design or teleological

phe-nomena Actions or objects are purposeful when the end state or goal is

consciously intended by an agent Thus, a man mowing his lawn is actingteleologically in the purposeful sense; a lion hunting deer and a bird build-ing a nest have at least the appearance of purposeful behavior Objects

resulting from purposeful behavior exhibit artificial (or external) teleology.

A knife, a table, a car, and a thermostat are examples of systems exhibitingartificial teleology: their teleological features were consciously intended bysome agent

Systems with teleological features that result not from the purposeful

ac-tion of an agent but from some natural process exhibit natural (or internal )

teleology The wings of birds have a natural teleology; they serve an end –flying – but their configuration is not due to the conscious design of any

agent We may distinguish two kinds of natural teleology: bounded, or

deter-minate, or necessary teleology; and unbounded, or indeterdeter-minate, or contingent

teleology

Bounded natural teleology exists when a specific end state is reached

in spite of environmental fluctuations The development of an egg into achicken is an example of bounded natural teleological process The regu-lation of body temperature in a mammal is another example In general,the homeostatic processes of organisms are instances of bounded naturalteleology.13

Unbounded design, or contingent teleology, occurs when the end state

is not specifically predetermined but rather is the result of selection of one

from among several available alternatives The adaptations of organisms aredesigned, or teleological, in this indeterminate sense The wings of birdscall for teleological explanation: the genetic constitutions responsible fortheir configuration came about because wings serve to fly and because flyingcontributes to the reproductive success of birds But there was nothing inthe constitution of the remote ancestors of birds that would necessitate theappearance of wings in their descendants Wings came about as the conse-quence of a long sequence of events At each stage, the most advantageousalternative was selected among those that happened to be available; butwhich alternatives were available at any one time depended, at least in part,

the possible exception of the flatworm Caenorhabditis elegans The ment of Drosophila fruitflies has also become known in much detail, even if

develop-not yet completely.) It is also possible, in principle, to describe the causalprocesses by which one genetic variant becomes eventually established in apopulation by natural selection But these causal explanations do not make

it unnecessary to provide teleological explanations where appropriate Bothteleological and causal explanations are called for in such cases

Paley’s claim that the design of living beings evinces the existence of aDesigner was shown to be erroneous by Darwin’s discovery of the process ofnatural selection, just as the pre-Copernican explanation for the motions ofcelestial bodies (and the argument for the existence of God based on the un-moved mover) was shown to be erroneous by the discoveries of Copernicus,Galileo, and Newton There is no more reason to consider Darwin’s the-ory of evolution and explanation of design anti-Christian than to considerNewton’s laws of motion anti-Christian Divine action in the universe must

be sought in ways other than those that postulate it as the means to accountfor gaps in the scientific account of the workings of the universe

Since the Copernican and Darwinian revolutions, all natural objects andprocesses have become subjects of scientific investigation Is there any im-portant missing link in the scientific account of natural phenomena? I be-lieve there is – namely, the origin of the universe The creation or origin

of the universe involves a transition from nothing into being But a tion can only be scientifically investigated if we have some knowledge aboutthe states or entities on both sides of the boundary Nothingness, however,

transi-is not a subject for scientific investigation or understanding Therefore, as