Teleological argument what is it

Intention, intervention, and other agency components of explanations can very frequently be pushed back to prior levels—much as many defenders of teleological arguments claim. The earlier case of the alleged poisoning of the rich uncle by the niece is a simple example of this. But in some cases, the specifics of the agent explanation in question may make appeal to some prior level less plausible or sensible. For example, suppose that one held the view that crop circles were to be explained in terms of direct alien activity.

One could, upon getting irrefutable video proof of human production of crop circles, still maintain that aliens were from a distance controlling the brains of the humans in question, and that thus the responsibility for crop circles did still lie with alien activity. While this retreat of levels preserves the basic explanation, it of course comes with a significant cost in inherent implausibility.

And in some cases, pushing specific agency back a level seems nearly unworkable. Suppose that the standard explanation of global warming was human activity, but that subsequently a complete, completely adequate, nailed down explanation in terms of solar cycles emerged. That would seem to explain away the alleged human causation, and in this sort of case it would be difficult to retreat back one level and make the case that human agency and activity were actually driving the solar cycles.

Still the level-changing possibility is as a general rule available with proposed agent explanations. And design typically is, of course, an agent explanation. In many attempted mechanistic relocation cases, it is difficult to see how the specific relocated explanatory factor is even supposed to work, much less generate any new explanatory traction.

Exactly what would caloric do if pushed back one level, for instance? Although level shifting of specific explanatory factors seems to work less easily within purely physical explanations, relocation attempts involving broad physical principles can sometimes avoid such difficulties.

For instance, for centuries determinism was a basic background component of scientific explanations apparently stochastic processes being explained away epistemically.

Then, early in the 20th century physics was largely converted to a quantum mechanical picture of nature as involving an irreducible indeterminism at a fundamental level—apparently deterministic phenomena now being what was explained away. However, DeBroglie, Bohm and others even for a time Einstein tried to reinstate determinism by moving it back to an even deeper fundamental level via hidden variable theories. Although the hidden variable attempt is generally thought not to be successful, its failure is not a failure of principle.

How one assesses the legitimacy, plausibility, or likelihood of the specific counter-explanation will bear substantial weight here, and that in turn will depend significantly on among other things background beliefs, commitments, metaphysical dispositions, and the like. Tilting the conceptual landscape via prior commitments is both an equal opportunity epistemic necessity and a potential pitfall here. Insisting on pushing an explanatory factor back a level is often an indication of a strong prior commitment of some sort.

Disagreement over deeper philosophical or other principles will frequently generate divergence over when something has or has not been explained away. One side, committed to the principle, will accept a level change as embodying a deeper insight into the relevant phenomenon. Returning to the present issue, design argument advocates will of course reject the claim that design, teleology, agency and the like have been explained away either by science generally or by Darwinian evolution in particular.

Reasons will vary. Some will see any science—Darwinian evolution included—as incompetent to say anything of ultimate design relevance, pro or con.

Many on both sides of the design issue fit here. Some will argue that a Darwinian failure occurs at d , citing e. Some intelligent design advocates e. However, the major contention of present interest involves e. Historically, design cases were in fact widely understood to allow for indirect intelligent agent design and causation, the very causal structures producing the relevant phenomena being themselves deliberately designed for the purpose of producing those phenomena. Paley himself, the authors of the Bridgewater Treatises and others were explicitly clear that whether or not something was designed was an issue largely separable from the means of production in question.

Historically it was insisted that design in nature did track back eventually to intelligent agency somewhere and that any design we find in nature would not—and could not—have been there had there ultimately been no mind involved. But commentators including many scientists at least from the early 17th century on e. For instance, over two centuries before Darwin, Bacon wrote:. Indeed, if the R s in question did directly indicate the influence of a mind, then means of production—whether unbroken causation or gappy—would be of minimal evidential importance.

However, if R s result from gapless chains of natural causal processes, the evidential impact of those R s again threatens to become problematic and ambiguous, since there will a fortiori be at the immediate level a full natural causal account for them. But even if such conceptions were explanatorily and scientifically superfluous at that level, that does not entail that they are conceptually, alethically, inferential, or otherwise superfluous in general.

The role of mind might be indirect, deeply buried, or at several levels of remove from the immediate production mechanism but would still have to be present at some level. In short, on the above picture Darwinian evolution will not meet condition e for explaining away design, which is not itself a shortcoming of Darwinian evolution.

But any gap-free argument will depend crucially upon the R s in question being ultimately dependent for their eventual occurrence upon agent activity. That issue could be integrated back into an altered Schema 2 by replacing 6 with:. The focus must now become whether or not the laws and conditions required for the indirect production of life, intelligent life, etc.

In recent decades, exactly that question has arisen increasingly insistently from within the scientific community. Intuitively, if the laws of physics were different, the evolution of life would not have taken the same path. If gravity were stronger, for example, then flying insects and giraffes would most likely not exist. The truth is far more dramatic. Even an extraordinarily small change in one of many key parameters in the laws of physics would have made life impossible anywhere in the universe.

Consider two examples:. If it were slightly less, the Big Bang would have quickly led to a Big Crunch in which the universe collapsed back onto itself. Life depends on, among other things, a balance of carbon and oxygen in the universe.

If the strong nuclear force were different by 0. Many examples of fine-tuning have to do with star formation. Stars are important since life requires a variety of elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus.

Stars contain the only known mechanism for producing large quantities of these elements and are therefore necessary for life. Lee Smolin estimates that when all of the fine-tuning examples are considered, the chance of stars existing in the universe is 1 in 10 Smolin is not merely claiming that all improbable events require an explanation, but some improbable events are special.

In poker, every set of five cards dealt to the dealer has the same probability, assuming that the cards are shuffled sufficiently. If the dealer is dealt a pair on three successive hands, no special explanation is required. Physicists who have written on fine-tuning agree with Smolin that it cries out for an explanation.

One explanation is that the universe appears to be fine-tuned for the existence of life because it literally has been constructed for life by an intelligent agent. There are two other types of responses to fine-tuning: i it does not, in fact, require a special explanation, and ii there are alternative explanations to theistic design. Three approaches have been taken to undermine the demand for explanation presented by fine-tuning.

In a sense, it is necessary for the fine-tuned constants to have values in the life-permitting range: If those values were not within that range, people would not exist. The fine-tuned constants must take on the values that they have in order for scientists to be surprised by their discovery in the first place.

As a matter of fact, they could not have discovered anything else. According to the weak anthropic principle, we ought not be surprised by having made such a discovery, since no other observation was possible. But if we should not have been surprised to have made such a discovery, then there is nothing unusual here that requires a special explanation.

The demand for explanation is simply misplaced. Sober gives a related but stronger argument based on observational selection effects Sober , 77— Say that Jones nets a large number of fish from a local lake, all of which are over 10 inches long.

Now say that Jones discovers that his net is covered with 10 inch holes, preventing him from capturing any smaller fish. In that case, e does not favor one hypothesis over the other. The evidence e is an artifact of the net itself, not a random sample of the fish in the lake. While intuitively. Since human observers could only detect constants in the life-permitting range, Sober argues, the correct probabilities are. Given this equality, fine-tuning does not favor h design over h chance.

The selection effect prevents any confirmation of design. Also see Jantzen a, sec. We should note that if Sober is correct, then the naturalistic explanations for fine-tuning considered below 4. If we assume that nature is not biased toward one value of C rather than another, then each unit subinterval in this range should be assigned equal probability.

Fine-tuning is surprising insofar as the life-permitting range of C is tiny compared to the full interval, which corresponds to a very small probability. As McGrew, McGrew, and Vestrup argue , there is a problem here in that, strictly speaking, mathematical probabilities do not apply in these circumstances. When a probability distribution is defined over a space of possible outcomes, it must add up to exactly 1.

But for any uniform distribution over an infinitely large space, the sum of the probabilities will grow arbitrarily large as each unit interval is added up. Since the range of C is infinite, McGrew et al. One solution to this problem is to truncate the interval of possible values.

A probability distribution could then be defined over the truncated range. A more rigorous solution employs measure theory. Measure is sometimes used in physics as a surrogate for probability. For example, there are many more irrational numbers than rational ones. Falling over is to be expected. In contrast, if a property that has zero measure in the relevant space were actually observed to be the case, like the pin continuing to balance on its tip, that would demand a special explanation.

The argument for fine-tuning can thus be recast such that almost all values of C are outside of the life-permitting range. The fact that our universe is life-permitting is therefore in need of explanation. The question of whether probabilities either do not apply or have been improperly applied to cosmological fine-tuning continues to draw interest.

Manson argues that neither theism nor naturalism provides a better explanation for fine-tuning. Assuming that fine-tuning does require an explanation, there are several approaches one might take Koperski , section 2.

That the universe is fine-tuned for life is based on current science. But, just as many other anomalies have eventually been explained, so might fine-tuning. Science may one day find a naturalistic answer, eliminating the need for design. For suggestions along these lines, see Harnik, Kribs, and Perez and Loeb While this is a popular stance, it is, of course, a promissory note rather than an explanation. The appeal to what might yet be discovered is not itself a rival hypothesis.

In other words, there may be exotic forms of life that could survive in a very different sort of universe. If so, then perhaps the parameter intervals that are in fact life-permitting are not fine-tuned after all.

The main difficulty with this suggestion is that all life requires a means for overcoming the second law of thermodynamics. Life requires the extraction of energy from the environment. Any life-form imaginable must therefore have systems that allow for something like metabolism and respiration, which in turn require a minimal amount of complexity e. Many examples of fine-tuning do not allow for such complexity, however. If there were no stars, for example, then there would be no stable sources of energy and no mechanism for producing the heavier elements in the periodic table.

Such a universe would lack the chemical building blocks needed for a living entity to extract energy from the environment and thereby resist the pull of entropy. While the odds of winning a national lottery are low, your odds would obviously increase if you were to buy several million tickets. The same idea applies to the most popular explanation for fine-tuning: a multiverse.

Perhaps physical reality consists of a massive array of universes each with a different set of values for the relevant constants. If there are many—perhaps infinitely many—universes, then the odds of a life-permitting universe being produced would seem to be much greater. While most of the universes in the multiverse would be unfit for life, so the argument goes, ours is one of the few where all of the constants have the required values.

While the philosophical literature on the multiverse continues to grow see Collins , and Kraay , many of the arguments against it share a common premise: a multiverse would not, by itself, be a sufficient explanation of fine-tuning.

More would have to be known about the way in which universes are produced. If the wheel is rigged in some way—by using magnets for example—to prevent that outcome, then the probability might be extremely small. If the table were rigged and yet Red 25 was the actual winner, that would require a special explanation. Likewise, if a property has zero measure in the space of possible universes, and yet that property is observed, its existence would still require an explanation Earman , This is true regardless of whether the space of universes is finitely or infinitely large.

In order to explain fine-tuning, the multiverse proponent would still have to show that the life-permitting universes do not have zero measure in the space of all universes Koperski , — A high-profile development in design arguments over the past 20 years or so involves what has come to be known as Intelligent Design ID. Although there are variants, it generally involves efforts to construct design arguments taking cognizance of various contemporary scientific developments primarily in biology, biochemistry, and cosmology —developments which, as most ID advocates see it, both reveal the inadequacy of mainstream explanatory accounts condition a and offer compelling evidence for design in nature at some level condition e again.

ID advocates propose two specialized R s— irreducible complexity Behe and specified complex information Dembski , The movement has elicited vociferous criticism and opposition. Opponents have pressed a number of objections against ID including, inter alia contentions that ID advocates have simply gotten the relevant science wrong, that even where the science is right the empirical evidences cited by design advocates do not constitute substantive grounds for design conclusions, that the existence of demonstrably superior alternative explanations for the phenomena cited undercuts the cogency of ID cases, and that design theories are not legitimate science , but are just disguised creationism, God-of-the-gaps arguments, religiously motivated, etc.

We will not pursue that dispute here except to note that even if the case is made that ID could not count as proper science, which is controversial, [ 14 ] that would not in itself demonstrate a defect in design arguments as such.

Science need not be seen as exhausting the space of legitimate conclusions from empirical data. In any case, the floods of vitriol in the current ID discussion suggest that much more than the propriety of selected inferences from particular empirical evidences is at issue.

That question is: why do design arguments remain so durable if empirical evidence is inferentially ambiguous, the arguments logically controversial, and the conclusions vociferously disputed? One possibility is that they really are better arguments than most philosophical critics concede. Another possibility is that design intuitions do not rest upon inferences at all.

The situation may parallel that of the existence of an external world, the existence of other minds, and a number of other familiar matters. The 18th century Scottish Common Sense philosopher Thomas Reid and his contemporary followers argued that we are simply so constructed that in certain normally-realized experiential circumstances we simply find that we in fact have involuntary convictions about such a world, about other minds, and so forth.

That would explain why historical philosophical attempts to reconstruct the arguments by which such beliefs either arose or were justified were such notorious failures—failures in the face of which ordinary belief nonetheless proceeded happily and helplessly onward.

If a similar involuntary belief-producing mechanism operated with respect to intuitions of design, that would similarly explain why argumentative attempts have been less than universally compelling but yet why design ideas fail to disappear despite the purported failure of such arguments.

A number of prominent figures historically in fact held that we could determine more or less perceptually that various things in nature were candidates for design attributions—that they were in the requisite respects design- like. Some, like William Whewell, held that we could perceptually identify some things as more than mere candidates for design Whewell , If something like that were the operative process, then ID, in trying to forge a scientific link to design in the sense of inferences from empirically determined evidences would be misconstructing the actual basis for design belief, as would be design arguments more generally.

It is perhaps telling, in this regard, that scientific theorizing typically involves substantial creativity and that the resultant theories are typically novel and unexpected. Design intuitions, however, do not seem to emerge as novel construals from creative grappling with data, but are embedded in our thinking nearly naturally—so much so that, again, Crick thinks that biologists have to be immunized against it.

Perception and appreciation of the incredible intricacy and the beauty of things in nature—whether biological or cosmic—has certainly inclined many toward thoughts of purpose and design in nature, and has constituted important moments of affirmation for those who already accept design positions. Possibility :Aliens??? Possibility: Universe making contest amongst multiple deities!!! Criticisms by David Hume:.

By David Hume:. The universe does not exhibit that much order as there are many indications of disorder such as the collision of galaxies, black holes, nova and supernova, cosmic radiation, gamma radiation, meteor impacts, volcanoes, earthquakes. See this site for counter arguments to creationism.

David Hume, - , argued against the Design Argument through an examination of the nature of analogy. Analogy compares two things, and, on the basis of their similarities, allows us to draw conclusions about the objects.

The more closely each thing resembles the other, the more accurate the conclusion. Have you ever heard the expression you are comparing apples to oranges? We use the above-mentioned idiom when we want to express the notion that a comparison is not accurate due to that dissimilarity of things under scrutiny.

A good analogy will not compare apples to oranges. Is the universe similar to a created artifact? Are they similar enough to allow for a meaningful analogy. Hume argues that the two are so dissimilar as to disallow analogy. Further, we know so very little about the universe that we can not compare it to any created thing that is within our knowledge.

If we want to employ a valid analogy between, say, the building of a house and the building of the universe we must be able to have an understanding of both terms. Since we can not know about the building of the universe a Design Analogy for the existence of God is nothing more than a guess. Links to websites on David Hume. Notes on Critiques of this Argument:. See also Logic of the Teleological Argument. In recent years a number of scientists have attempted to supply a variation on the teleological argument that is also a counter to the evolutionary theory.

It is called Intelligent Design Theory. This theory disputes that the process of natural selection, the force Darwin suggested drove evolution, is enough to explain the complexity of and within living organisms. This theory holds that the complexity requires the work of an intelligent designer.

The designer could be something like the Supreme Being or the Deity of the Scriptures or it could be that life resulted as a consequence of a meteorite from elsewhere in the cosmos, possibly involving extraterrestrial intelligence, or as in new age philosophy that the universe is suffused with a mysterious but inanimate life force from which life results.

One of its weaknesses is that the argument for intelligent design is subject to a great many definitions: what is intelligent design? Opponents of this argument will point out that rather than looking to see if an object looks as if it were designed, we should look at it and determine if its origin could have been natural.

Well designed compared to what? The universe is terribly complex, vastly interesting, awe-inspiring—but, as far as we can tell, it is the only one. Most people who bring this one up have in mind some variation of a creationist argument in response to Darwin or other evolutionary theorists.

The one usually credited with popularizing or developing this version is William Paley, who described it in Natural Theology Daniel C. The natural forces at work in the universe do change things, and at least in the case of organic matter, those changes are in a particular direction, or directions.

But that does not imply purpose or an intentional destination. Given a few million generations over a few billion years, such design forces can create an astonishing variety of interesting products—but that in no way suggests an omnipotent, omniscient, purposeful Creator. Counter argument to the teleological argument based on Complexity or Improbability. The more the complexity of the universe or the improbability of its actual orderings then the less likely it is that it had or has an intelligent designer.

The case made by the promoters of the intelligent design argument is actually providing evidence against the conclusion that there must be an intelligent designer. The more the complexity of the universe is advocated or presented by the promoters of the intelligent design argument as a supposed indication of intelligence at work, then the more it works against the conclusion that there must be an intelligent designer.

Because i f there was an intelligent designer there would be no need for all the complexity and waste observed in the physical universe. Who Owns the Argument from Improbability? The more improbable the specified complexity, the more improbable the god capable of designing it. Darwinism comes through the regress unscathed, indeed triumphant.

Improbability, the phenomenon we seek to explain, is more or less defines as that which is difficult to explain. It is obviously self-defeating to try to explain it by invoking a creative being of even greater complexity. Darwinism really does explain complexity in terms of something simpler-which in turn is explained in terms of something simpler still, and so on back to the primeval simplicity. It is the gradual escalatory quality of non-random natural selection that arms the Darwinian theory against the menace of infinite regress.

Design is the temporarily correct explanation for some particular manifestation of specified complexity such as a car or a washing machine. It could conceivably turn out that …. The argument from probability, properly applied, rules out their spontaneous existence de novo.

Sooner or later we are going to have to terminate the regress with something more explanatory than design itself. Design can never be an ultimate explanation. And-here is the point of my title-the more statistically improbable the specified complexity, the more inadequate does the design theory become, while the explanatory work done by the crane of gradualistic natural selection becomes correspondingly more indispensable.

The argument from improbability firmly belongs to the evolutionists. It is our strongest card, and we should instantly turn it against our political opponents we have no scientific opponents whenever they try to play it against us.

Dennett, Daniel C. Dawkins, Richard. Hume, David. Paley, William. Pigliucci, Massimo. Tales of the Rational , Freethought Press, Stein, Gordon, ed. A Critique of Intelligent Design Theory:. The "Intelligent Design ID Movement" is comprised of a diverse group of persons - including philosophers, lawyers, theologians, public policy advocates, and scientific or technical professionals - who believe that contemporary evolutionary theory is inadequate to explain the diversity and complexity of life on Earth.

They argue that a full scientific explanation of the structures and processes of life requires reference to an intelligent agent beyond nature. The ID Movement seeks to modify public science education policy at state and local levels to allow inclusion of the Movement's critiques of evolutionary theory and its assertions of an extra-natural origin of biological diversity and complexity.

Institutionally, the Movement is supported by the Center for Science and Culture of the Discovery Institute and has also created its own virtual professional society to promote its views. However, all other relevant professional scientific organizations judge the ID Movement to be outside of mainstream science and its theoretical proposals to be unwarranted on the basis of observations from nature and laboratory experiments.

The contemporary theory of biological evolution is one of the most robust products of scientific inquiry. A single muscle with a straight tendon, which is the common muscular form, would have been sufficient, if it had had power to draw far enough. But the contraction, necessary to draw the membrane over the whole eye, required a longer muscle than could lie straight at the bottom of the eye.

Therefore, in order to have a greater length in a less compass, the cord of the main muscle makes an angle. This, so far, answers the end; but, still further, it makes an angle, not round a fixed pivot, but round a loop formed by another muscle; which second muscle, whenever it contracts, of course twitches the first muscle at the point of inflection, and thereby assists the action designed by both. In mammals, the recurrent laryngeal nerve provides a connection between the brain and the larynx, though not a direct one.

Instead of taking a direct route, it passes down into the chest, circles under the aorta, and ascends back up to the neck in giraffes, this nerve is more than 2 meters long; Harrison Similarly, the mammalian vas deferens connects the testes to the urethra, but not before passing into the pelvic cavity, looping around the urinary bladder and then descending back to complete its circuitous path.

Meanwhile, the urethra itself passes directly through the prostate gland, an arrangement that readily engenders urinary difficulties if the prostate becomes swollen. It is only with great effort that arrangements such as these might be characterized as optimizations rather than as simple quirks of evolutionary history Footnote 10 for additional examples, see Williams ; Shubin ; Coyne But why bother with eyes at all?

If the designer is omnipotent, why does the detection of visual information require such a complex arrangement of lenses, receptors, nerves, muscles, and neurons? Why make the difficulty in order to surmount it?

If to perceive objects by some other mode than that of touch, or objects which lay out of the reach of that sense, were the thing proposed; could not a simple volition of the Creator have communicated the capacity? Why resort to contrivance, where power is omnipotent?

Contrivance, by its very definition and nature, is the refuge of imperfection. To have recourse to expedients, implies difficulty, impediment, restraint, defect of power. 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; I mean as our rational faculties are formed at present.

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. God, therefore, has been pleased to prescribe limits to his own power, and to work his end within those limits.

According to Paley, the exquisite function of eyes bespeaks the great power of a designer, but the very decision to create eyes reflects an intentional limitation of this power so that humans might understand how eyes came to be. This logic may strike the modern reader as rather tortuous, but it serves to illustrate a very important point: that any explanation for complex organs must account not only for their adaptive characteristics but also their imperfections.

Today, this duality can be accounted for by the countervailing influences of adaptive modification and the constraints of genetics, anatomy, and history, but for Paley, the intent of a designer provided the only conceivable answer. As noted, Paley did not consider imperfections to challenge the conclusion that design indicates the work of a designer. It is only if one wishes to defend the infallibility of the designer that one must assume all features of an object to be functional, and optimally so see pp.

Again, this represents something of a more sophisticated application of the argument from design than is often encountered in contemporary discourse. Whereas genetic mutation is both integral to the process and indeed is random with respect to its effects, natural selection is, by definition, the nonrandom survival and reproduction of individuals. Variation is generated at random, but whether or not it is preserved depends on its effects on survival and reproduction within a given environment Footnote 11 for reviews, see Gregory , No serious evolutionary biologist of the past years has suggested that the emergence of complex organs is merely the result of chance.

Writing as he did before Darwin and Wallace proposed the theory of natural selection, it was not possible for Paley to make this error modern neo-Paleyans, by contrast, do so with remarkable proficiency. In the early s, chance was not the only suggested alternative to conscious design McLaughlin , but Paley viewed its refutation as an important part of his argument. Paley and Darwin understood that chance plays a role in nature, but that it is incapable of producing adaptive complexity:.

What does chance ever do for us? In the human body, for instance, chance, i. Amongst inanimate substances, a clod, a pebble, a liquid drop might be; but never was a watch, a telescope, an organized body of any kind, answering a valuable purpose by a complicated mechanism, the effect of chance.

Modern evolutionary biologists do not part company with Paley on the claim that complex organs must arise through a mechanism other than pure chance. Paley takes his argument against the role of chance a step farther, in the process raising—and summarily rejecting—a possible explanation that exhibits shades of the principle of natural selection.

However, his description is of an ancient version of the idea that, as Paley rightly notes, is unworkable in practice. Footnote There is another answer which has the same effect as the resolving of things into chance; which answer would persuade us to believe, that the eye, the animal to which it belongs, every other animal, every plant, indeed every organized body which we see, are only so many out of the possible varieties and combinations of being, which the lapse of infinite ages has brought into existence; that the present world is the relict of that variety: millions of other bodily forms and other species having perished, being by the defect of their constitution incapable of preservation, or of continuance by generation.

Now there is no foundation whatever for this conjecture in any thing which we observe in the works of nature; no such experiments are going on at present: no such energy operates, as that which is here supposed, and which should be constantly pushing into existence new varieties of beings.

Nor are there any appearances to support an opinion, that every possible combination of vegetable or animal structure has formerly been tried. Multitudes of conformations, both of vegetables and animals, may be conceived capable of existence and succession, which yet do not exist. Perhaps almost as many forms of plants might have been found in the fields, as figures of plants can be delineated upon paper. A countless variety of animals might have existed, which do not exist.

Upon the supposition here stated, we should see unicorns and mermaids, sylphs and centaurs, the fancies of painters, and the fables of poets, realized by examples. Or, if it be alleged that these may transgress the limits of possible life and propagation, we might, at least, have nations of human beings without nails upon their fingers, with more or fewer fingers and toes than ten, some with one eye, others with one ear, with one nostril, or without the sense of smelling at all.

All these, and a thousand other imaginable varieties, might live and propagate. We may modify any one species many different ways, all consistent with life, and with the actions necessary to preservation, although affording different degrees of conveniency and enjoyment to the animal.

And if we carry these modifications through the different species which are known to subsist, their number would be incalculable. No reason can be given why, if these deperdits ever existed, they have now disappeared. Yet, if all possible existences have been tried, they must have formed part of the catalogue.

The problem, of course, is not the notion that great variety may arise by chance and be narrowed by differential survival—this is the basis of natural selection as it is now understood.

Specifically, he envisioned an unconstrained morphospace in which drastically divergent species continually pop into existence. According to Paley, the classification of species into larger taxa would be rendered impossible by widespread extinction. In fact, the major divisions among extant lineages are now understood to exist precisely because so many ancestors and intermediate forms have perished.

The preceding arguments occupy only the first six of the 27 chapters in Natural Theology. In Chapters 7 through 20, Paley leads the reader on an expedition through the annals of early nineteenth century biological knowledge as he understands it, pausing along the way to admire the elegance of the bones Chapter 8 , muscles Chapter 9 , blood vessels Chapter 10 , and digestive systems Chapters 7 and 10 of vertebrates, as well as features of insects Chapter 19 and plants Chapter 20 which, though less well understood, he also described as bearing the hallmarks of design.

Similarly, Paley takes a broad comparative approach that would be at home in modern evolutionary biology were it interpreted from a different perspective. He recognizes that specializations for particular lifestyles reflect modifications of traits shared by many animals.

He grasps the unity of underlying body plans. And he notes that though it dissipates among groups living in widely divergent habitats, the similarity does not disappear.

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 plan and such adaptation, the strongest evidence that can be afforded of intelligence and design; an evidence which most completely excludes every other hypothesis. 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?

Very much of this reasoning is applicable to what has been called Comparative Anatomy. In their general economy, in the outlines of the plan, in the construction as well as offices of their principal parts, there exists between all large terrestrial animals a close resemblance. In all, life is sustained, and the body nourished by nearly the same apparatus.

The heart, the lungs, the stomach, the liver, the kidneys, are much alike in all. The same fluid for no distinction of blood has been observed circulates through their vessels, and nearly in the same order.

The same cause, therefore, whatever that cause was, has been concerned in the origin, has governed the production of these different animal forms. When we pass on to smaller animals, or to the inhabitants of a different element, the resemblance becomes more distant and more obscure; but still the plan accompanies us.

These, like functional traits shared more broadly, also reflect the remarkable fit of species to their environments which Paley takes as strong evidence for their origin by design.

I can hardly imagine to myself a more distinguishing mark, and, consequently, a more certain proof of design, than preparation , i.

The teeth of mammals, the milk that nourishes their young, their eyes that develop while still in the darkness of the womb, and their lungs that form before encountering any opportunity to draw a breath—in the absence of knowledge about developmental genetics, these struck Paley as especially weighty examples of foresightful design.

Paley does not only rely on individual examples of function to support his position. In addition, he expounds upon the close interaction of parts in service of a specific function.

He returns to the analogy of the watch in this capacity at the opening of Chapter When several different parts contribute to one effect; or, which is the same thing, when an effect is produced by the joint action of different instruments; the fitness of such parts or instruments to one another, for the purpose of producing, by their united action the effect, is what I call relation: and wherever this is observed in the works of nature or of man, it appears to me to carry along with it decisive evidence of understanding, intention, art.

In examining, for instance, the several parts of a watch , the spring, the barrel, the chain, the fusee, the balance, the wheels of various sizes, forms, and positions, what is it which would take an observer's attention, as most plainly evincing a construction, directed by thought, deliberation, and contrivance?

It is the suitableness of these parts to one another; first, in the succession and order in which they act; and, secondly, with a view to the effect finally produced. Paley is especially taken by close interactions among independent components which today are explained as the product of co-evolution :. But relation perhaps is never so striking as when it subsists, not between different parts of the same thing, but between different things.

The relation between a lock and a key is more obvious, than it is between different parts of the lock. A bow was designed for an arrow, and an arrow for a bow: and the design is more evident for their being separate implements. Nor do the works of the Deity want this clearest species of relation. The sexes are manifestly made for each other.

They form the grand relation of animated nature; universal, organic, mechanical; subsisting like the clearest relations of art, in different individuals; unequivocal, inexplicable without design.

So much so, that, were every other proof of contrivance in nature dubious or obscure, this alone would be sufficient. The example is complete. Nothing is wanting to the argument.