Teleological arguments get the name from the ancient Greek word telos, meaning something like ‘purpose’ or ‘goal’. They are also known as design arguments because they argue that there is evidence of of design in nature, like how the eye seems designed for vision or a heart seems designed to pump blood. And if these things are designed, there must be a designer who made these designs: God.

The history of teleological arguments can be traced back at least to the ancient Greeks. Aristotle’s metaphysics from the 4th century BC – particularly his concept of final causes – laid the foundation for Thomas Aquinas‘ teleological argument (the 5th way) in the 13th Century. But in the centuries that followed, the scientific revolution challenged the Aristotelian framework underpinning Aquinas’s reasoning. As such, later thinkers – such as David Hume and William Paley – revised the teleological argument within the emerging scientific paradigm of their time. However, in the 19th Century, Darwin’s theory of evolution shook the scientific foundations of teleological arguments once again by providing an explanation of the apparent design in nature without the need for a designer. Since Darwin, modern teleological arguments often focus on the apparent design of the laws of nature – such as gravity and electromagnetism – as these can’t be explained by evolution.

This post goes through some of the most well-known versions of teleological arguments and contrasts them against various issues and objections. If you’re looking for a specific argument or objection you can jump straight to it using the links below:

Aquinas’ 5th Way

“The fifth way is taken from the governance of the world. We see that things which lack intelligence, such as natural bodies, act for an end, and this is evident from their acting always, or nearly always, in the same way, so as to obtain the best result. Hence it is plain that not fortuitously, but designedly, do they achieve their end. Now whatever lacks intelligence cannot move towards an end, unless it be directed by some being endowed with knowledge and intelligence; as the arrow is shot to its mark by the archer. Therefore some intelligent being exists by whom all natural things are directed to their end; and this being we call God.”

– Aquinas, Summa Theologica

plant growing teleological argumentAquinas’ 5th Way, written in the 13th Century in Summa Theologica, argues that natural objects act in consistent, goal-directed ways, even without consciousness or intelligence. For example, plants grow toward the sun to maximise the light needed for photosynthesis.

Such purposeful behaviour regularly cannot be attributed to mere chance, says Aquinas – there has to be an intelligence guiding these things to their goals in the same way an archer guides an arrow to its target. These non-intelligent things require an external intelligence to direct them toward their goals.

Aquinas concludes that this guiding intelligence is God.

Problem: The scientific revolution

Aquinas’s 5th Way assumes the scientific paradigm of the day, which was shaped by Aristotle. According to Aristotle’s metaphysics, everything in the universe has a purpose (telos), and this explains why things behave as they do. For example, a seed grows into a plant because its telos is to reach full development and reproduce. A stone falls to the ground because its natural place is at the centre of the Earth.

But, following the scientific revolution of the 16th Century, the Newtonian paradigm replaced this Aristotelian paradigm. Rather than explaining phenomena in terms of telos – in terms of an inherent goal, purpose, or deliberate intention – this new approach described phenomena through impersonal, mechanistic laws. For example, the seed grows into a plant because of biochemical processes: Energy from sunlight, photosynthesis, water and minerals from the soil providing nutrients, genetic instructions in the plant’s DNA guiding development, and so on. The stone falls to the ground because of gravity, not because of any intention or purpose or telos in the stone.

Aristotelian explanation Mechanistic explanation
The seed grows into a plant because that is its purpose/telos The seed grows into a plant because of genetic instructions in the DNA interacting with environmental factors
The rock falls to the ground because that is its purpose/telos The rock falls to the ground because of the force of gravity

Without the Aristotelian framework of goal-directedness in nature, the 5th Way loses its metaphysical foundation. This makes the inference to a designer less compelling – at least within this new scientific paradigm.

Possible response:

Not everything can be explained scientifically via impersonal and mechanistic laws. For example, Swinburne’s teleological argument (below) argues that science works by assuming scientific laws (e.g. gravity) to explain things, but that scientific explanations can’t explain why the laws themselves exist as they do.

Hume’s teleological argument from analogy

In Dialogues Concerning Natural Religion (1779), David Hume presents a teleological argument through the character Cleanthes:

“Look round the world: Contemplate the whole and every part of it: You will find it to be nothing but one great machine, subdivided into an infinite number of lesser machines, which again admit of subdivisions, to a degree beyond what human senses and faculties can trace and explain. All these various machines, and even their most minute parts, are adjusted to each other with an accuracy, which ravishes into admiration all men, who have ever contemplated them. The curious adapting of means to ends, throughout all nature, resembles exactly, though it much exceeds, the productions of human contrivance; of human design, thought, wisdom, and intelligence. Since therefore the effects resemble each other, we are led to infer, by all the rules of analogy, that the causes also resemble; and that the Author of nature is somewhat similar to the mind of man; though possessed of much larger faculties, proportioned to the grandeur of the work, which he has executed. By this argument a posteriori, and by this argument alone, do we prove at once the existence of a Deity, and his similarity to human mind and intelligence.”

– Hume, Dialogues Concerning Natural Religion

Hume’s argument here is an argument from analogy. It says that because two things are similar in some ways, then it’s reasonable to think they might be similar in other ways too. For example, if your friend likes the same art and music as you do, then, by analogy, it’s reasonable to expect they’ll like the same movies as you as well.

So this is what Hume/Cleanthes is arguing here. That the universe is like a machine in that it’s orderly, complex, and full of parts that serve particular functions. For example, the various parts of the eye are arranged in an orderly manner to achieve sight, the orbit of Earth around the sun is such that it provides a stable environment for life. There is a “fitting of means to ends” here and all over the universe. The universe is like a watch or a car or some other machine in these ways.

And since we know these machines – watches and cars – have designers who made them, then, by analogy, it’s reasonable to assume that the universe is also similar in that it has a designer too.

Man-made machines The universe
Parts accurately adjusted to each other Parts accurately adjusted to each other
Adapting of means to ends Adapting of means to ends
Designed by an intelligence/a mind Probably also designed by an intelligence/mind

And, says Cleanthes, given the scope of this design – given the grandeur of the entire universe compared to man-made designs like a watch or a car – this designer must be “possessed of much larger faculties, proportioned to the grandeur of the work”. In other words, the designer must be incredibly intelligent and powerful.

And so, argues Cleanthes, an incredibly intelligent and powerful designer – you might say an omnipotent and omniscient designer – exists. And so God exists.

Problem: Weaknesses in the analogy

As a dialogue, Hume also presents responses to his teleological argument in Dialogues Concerning Natural Religion through the character Philo. Firstly, Philo argues that the analogy between the universe and man-made machines is weak:

“But wherever you depart, in the least, from the similarity of the cases, you diminish proportionably the evidence; and may at last bring it to a very weak analogy, which is confessedly liable to error and uncertainty. After having experienced the circulation of the blood in human creatures, we make no doubt that it takes place in Titius and Mævius: But from its circulation in frogs and fishes, it is only a presumption, though a strong one, from analogy, that it takes place in men and other animals. The analogical reasoning is much weaker, when we infer the circulation of the sap in vegetables from our experience that the blood circulates in animals; and those, who hastily followed that imperfect analogy, are found, by more accurate experiments, to have been mistaken.”

– Hume, Dialogues Concerning Natural Religion

As Philo points out, arguments from analogy are only as strong as the similarity between the two things being compared:

  • If one human has circulating blood, we are justified in claiming that all humans do.
  • And further, we are also somewhat justified in generalising from circulation of blood in humans to frogs and fishes as well – although the analogy is weaker.
  • However, when the analogy goes from animals to plants, it’s much weaker and the idea that plants circulate sap like animals circulate blood is false.

A simpler example:

  • A lion is similar to a cat in that they are both fluffy mammals,
  • and cats make good pets,
  • but it doesn’t follow from this that a lion would also make a good pet.

Just because lions and cats are similar in some ways, it doesn’t prove they’re similar in all ways. There are a bunch of differences between cats and lions that weaken the inference to “lions also make good pets”. For example, a lion is not domesticated and is much larger and more aggressive.

Similarly, Philo points out a bunch of differences between man-made machines and the universe:

Man-made machines The universe
We have experience of seeing them being designed by minds We don’t have experience of seeing the universe being designed
Not alive, mechanical Full of life, biological
Clear purpose No clear purpose

So, while there are some similarities between man-made machines and the universe – like ‘fitting of means to ends’ – that justify the inference to the further similarity of design, there are more differences that weaken this inference:

  • Firstly, Philo notes that we have experience of human-made things being designed – like houses and watches – but no such experience of natural objects like eyes, hearts, or planets. What we do observe are natural processes such as reproduction and growth, which suggest a cause of the universe more like “generation and vegetation” than conscious design.
  • Secondly, the argument focuses only on the most ordered parts of nature, such as the human eye, and ignores the vast stretches of disorder and emptiness in the universe. While parts of the universe, like an eye, seem to have purpose and design like man-made items, when you look at the universe as a whole the analogy is much weaker.

Problem: Spatial disorder and design flaws

Teleological arguments point to examples of order in nature – things that are neatly organised to serve a purpose, like the parts of the eye to see – and use this as evidence for design and so a designer. But critics of teleological arguments point to examples of disorder and design flaws in nature, which should count as evidence against a designer.

Firstly, if we look at the universe as a whole, order appears to be the exception rather than the rule. For example, most of the universe is just empty space, most planets are uninhabitable with no life on them. There are asteroids and random rocks that don’t serve any obvious purpose. Why would a designer include so much unnecessary extra stuff in their design?

Secondly, we can point to examples of imperfections and design flaws here on Earth that an all-powerful and all-loving designer could seemingly improve upon. For example Hume, through the character Philo, argues that it would be better design for humans and animals to be motivated only by varying degrees of pleasure rather than pain:

“The first circumstance which introduces evil, is that contrivance or economy of the animal creation, by which pains, as well as pleasures, are employed to excite all creatures to action, and make them vigilant in the great work of self-preservation. Now pleasure alone, in its various degrees, seems to human understanding sufficient for this purpose. All animals might be constantly in a state of enjoyment: but when urged by any of the necessities of nature, such as thirst, hunger, weariness; instead of pain, they might feel a diminution of pleasure, by which they might be prompted to seek that object which is necessary to their subsistence. Men pursue pleasure as eagerly as they avoid pain; at least they might have been so constituted. It seems, therefore, plainly possible to carry on the business of life without any pain. Why then is any animal ever rendered susceptible of such a sensation? If animals can be free from it an hour, they might enjoy a perpetual exemption from it; and it required as particular a contrivance of their organs to produce that feeling, as to endow them with sight, hearing, or any of the senses.”

– Hume, Dialogues Concerning Natural Religion

Philo points out further seemingly simple improvements that a designer would make to the designs of nature. For example, giving humans greater strength and speed or, at the very least, less laziness:

“In order to cure most of the ills of human life, I require not that man should have the wings of the eagle, the swiftness of the stag, the force of the ox, the arms of the lion, the scales of the crocodile or rhinoceros; much less do I demand the sagacity of an angel or cherubim. I am contented to take an increase in one single power or faculty of his soul. Let him be endowed with a greater propensity to industry and labour; a more vigorous spring and activity of mind; a more constant bent to business and application. Let the whole species possess naturally an equal diligence with that which many individuals are able to attain by habit and reflection; and the most beneficial consequences, without any allay of ill, is the immediate and necessary result of this endowment. Almost all the moral, as well as natural evils of human life, arise from idleness; and were our species, by the original constitution of their frame, exempt from this vice or infirmity, the perfect cultivation of land, the improvement of arts and manufactures, the exact execution of every office and duty, immediately follow; and men at once may fully reach that state of society, which is so imperfectly attained by the best regulated government.”

– Hume, Dialogues Concerning Natural Religion

Thirdly, Philo says, even things in nature that do work well could be more finely tuned. The wind, for example, is useful in that it can power ships and windmills – but sometimes it’s too strong, leading to hurricanes that cause destruction and death. Similarly with rain: it’s necessary to enable plants to grow, but sometimes you get too little rain – i.e. droughts – where the plants can’t grow and sometimes you get too much – i.e. floods – which cause death and destruction. These systems and forces in nature constantly swing to extremes instead of staying within the precise limits you would expect from deliberate design:

“But at the same time, it must be observed, that none of these parts or principles, however useful, are so accurately adjusted, as to keep precisely within those bounds in which their utility consists; but they are, all of them, apt, on every occasion, to run into the one extreme or the other. One would imagine, that this grand production had not received the last hand of the maker; so little finished is every part, and so coarse are the strokes with which it is executed. Thus, the winds are requisite to convey the vapours along the surface of the globe, and to assist men in navigation: but how oft, rising up to tempests and hurricanes, do they become pernicious? Rains are necessary to nourish all the plants and animals of the earth: but how often are they defective? how often excessive? Heat is requisite to all life and vegetation; but is not always found in the due proportion. On the mixture and secretion of the humours and juices of the body depend the health and prosperity of the animal: but the parts perform not regularly their proper function. What more useful than all the passions of the mind, ambition, vanity, love, anger? But how oft do they break their bounds, and cause the greatest convulsions in society? There is nothing so advantageous in the universe, but what frequently becomes pernicious, by its excess or defect; nor has Nature guarded, with the requisite accuracy, against all disorder or confusion. The irregularity is never perhaps so great as to destroy any species; but is often sufficient to involve the individuals in ruin and misery.”

– Hume, Dialogues Concerning Natural Religion

So these examples of disorder and design flaws can be used as evidence against nature being designed. The pain and suffering of animals, the chaotic hurricanes, the droughts and floods, the large areas of empty space, etc. all seem more consistent with a purposeless universe formed via impersonal natural laws rather deliberate design choices.

Potential response:

In his teleological argument, Paley argues that even a watch that kept time poorly would still be evidence of design – you wouldn’t believe such a watch formed by chance simply because it didn’t work perfectly. And so, by analogy, Paley argues that apparent flaws or disorder in nature do not disprove design. Just as a broken or imperfect watch still requires a watchmaker, the complex order we see in nature – such as the intricate structure of the eye to achieve vision – still points to a designer, even if some parts of nature seem imperfect or chaotic.

“Every observation which was made in our first chapter, concerning the watch, may be repeated with strict propriety, concerning the eye; concerning animals; concerning plants; concerning, indeed, all the organized parts of the works of nature… When we are inquiring simply after the existence of an intelligent Creator, imperfection, inaccuracy, liability to disorder, occasional irregularities, may subsist in a considerable degree, without inducing any doubt into the question: just as a watch may frequently go wrong, seldom perhaps exactly right, may be faulty in some parts, defective in some, without the smallest ground of suspicion from thence arising that it was not a watch; not made; or not made for the purpose ascribed to it.”

– Paley, Natural Theology

Problem: The Epicurean hypothesis

“For instance, what if I should revive the old EPICUREAN hypothesis? This is commonly, and I believe justly, esteemed the most absurd system that has yet been proposed; yet I know not whether, with a few alterations, it might not be brought to bear a faint appearance of probability. Instead of supposing matter infinite, as EPICURUS did, let us suppose it finite. A finite number of particles is only susceptible of finite transpositions: and it must happen, in an eternal duration, that every possible order or position must be tried an infinite number of times. This world, therefore, with all its events, even the most minute, has before been produced and destroyed, and will again be produced and destroyed, without any bounds and limitations. No one, who has a conception of the powers of infinite, in comparison of finite, will ever scruple this determination.”

– Hume, Dialogues Concerning Natural Religion

Hume, again through the character Philo, introduces the Epicurean hypothesis – named after the ancient Greek philosopher Epicurus – as a potential way to explain the apparent design in nature without the need for an intelligent designer. He suggests that, given infinite time, matter will inevitably arrange itself into patterns that seem designed, simply through the sheer number of random configurations.

monkeys and typewriters epicurean hypothesisThe idea is a bit like the infinite monkeys with typewriters thought experiment: given an infinite amount of time, a monkey randomly hitting keys would eventually type the complete works of Shakespeare. The point is not that the monkey learns what to write. The point is that, with infinite time, every possible sequence of letters will occur eventually – including ones that look purposely designed.

The Epicurean hypothesis applies this same reasoning to the universe. Given infinite time, the random motion and rearrangement of matter will eventually produce stable, ordered structures – like eyes for seeing or hearts for pumping blood – entirely by chance. These arrangements only appear to be designed but in reality are no more the product of intelligence than the monkey’s lucky novel. We just happen to find ourselves in a rare patch of the universe where order exists, while for every ordered system, there are infinitely more disordered, chaotic ones.

Potential response:

Paley rejects the Epicurean hypothesis on the grounds that it doesn’t fit with what we actually observe in nature.

If life were simply the product of endless chance arrangements, he says, we would expect to see all sorts of strange and arbitrary creatures: unicorns, mermaids, humans with one eye, people without nails, and countless other bizarre variations that are perfectly compatible with life. Yet we don’t. Instead, the natural world is consistent and orderly, with plants and animals falling into clear, structured categories. Nor is there any evidence of an ongoing process where new, radically different life forms appear at random.

In short, if the Epicurean hypothesis were true, nature would be chaotic and unpredictable. However, in reality, nature is stable, patterned, and systematic – a state of affairs far better explained by intelligent design than by infinite chance.

“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.
But, moreover, the division of organized substances into animals and vegetables, and the distribution and sub-distribution of each into genera and species, which distribution is not an arbitrary act of the mind, but founded in the order which prevails in external nature, appear to me to contradict the supposition of the present world being the remains of an indefinite variety of existences; of a variety which rejects all plan. The hypothesis teaches, that every possible variety of being hath, at one time or other, found its way into existence (by what cause or in what manner is not said), and that those which were badly formed, perished; but how or why those which survived should be cast, as we see that plants and animals are cast, into regular classes, the hypothesis does not explain; or rather the hypothesis is inconsistent with this phænomenon.”

– Paley, Natural Theology

Problem: The universe is a unique case

Hume also rejects the inference to a designer on the grounds that the universe is a unique case.

We infer design in everyday life by comparing something to other things we already know are designed. We know a watch has a maker, for example, because we’ve seen many watches and know how they’re made. But with the universe, we have nothing to compare it to. We’ve only ever observed one universe – our own – and so we can’t say whether the kind of order we see here is the kind that comes from design or the kind that arises naturally:

“When two species of objects have always been observed to be conjoined together, I can infer, by custom, the existence of one wherever I see the existence of the other; and this I call an argument from experience. But how this argument can have place, where the objects, as in the present case, are single, individual, without parallel, or specific resemblance, may be difficult to explain. And will any man tell me with a serious countenance, that an orderly universe must arise from some thought and art like the human, because we have experience of it? To ascertain this reasoning, it were requisite that we had experience of the origin of worlds; and it is not sufficient, surely, that we have seen ships and cities arise from human art and contrivance.”

– Hume, Dialogues Concerning Natural Religion

Paley’s teleological argument

William Paley’s teleological argument, from Natural Theology (1802), uses the famous watchmaker comparison to argue for the existence of God. Paley begins by comparing a stone with a watch found in a field: while we might accept that a stone could have been there forever, we would never say the same of a watch.

“In crossing a heath, suppose I pitched my foot against a stone, and were asked how the stone came to be there, I might possibly answer, that, for any thing I knew to the contrary, it had lain there for ever: nor would it perhaps be very easy to shew the absurdity of this answer. But suppose I had found a watch upon the ground, and it should be enquired how the watch happened to be in that place, I should hardly think of the answer which I had before given, that, for any thing I knew, the watch might have always been there. Yet why should not this answer serve for the watch, as well as for the stone?

Paley watch argument
The pebble (left) does not have the key property of design, whereas the watch (right) does

The difference, he argues, is that a watch has multiple parts intricately arranged to fulfil a specific purpose – telling the time – and such purposeful arrangement is the hallmark of design. Anything with this property must have been designed, he says, and so must have a designer:

Why is it not as admissible in the second case, as in the first? For this reason, and for no other, viz. that, when we come to inspect the watch, we perceive (what we could not discover in the stone) that its several parts are framed and put together for a purpose, e.g. that they are so formed and adjusted as to produce motion, and that motion so regulated as to point out the hour of the day; that, if the several parts had been differently shaped from what they are, of a different size from what they are, or placed after any other manner, or in any other order, than that in which they are placed, either no motion at all would have been carried on in the machine, or none which would have answered the use, that is now served by it… the inference, we think, is inevitable, that the watch must have had a maker: that there must have existed, at some time, and at some place or other, an artificer or artificers who formed it for the purpose which we find it actually to answer; who comprehended its construction, and designed its use.”

– Paley, Natural Theology

Paley then points out that nature displays this same property – of having multiple parts arranged to fulfil a specific purpose. For example, the eye’s cornea, lens, muscles, and other components are all precisely arranged to enable sight, just as the parts of a watch are arranged to tell time:

“for every indication of contrivance, every manifestation of design, which existed in the watch, exists in the works of nature;…  I know no better method of introducing so large a subject, than that of comparing a single thing with a single thing; an eye, for example, with a telescope. As far as the examination of the instrument goes, there is precisely the same proof that the eye was made for vision, as there is that the telescope was made for assisting it.”

– Paley, Natural Theology

Although Paley does not state this explicitly, his teleological argument can be read as a deductive argument, in contrast to Hume’s argument from analogy (see this post for more detail on this difference). In deductive form, Paley’s teleological argument can be summarised like this:

  1. Anything that has multiple parts arranged for a purpose is designed
  2. The eye (and other things in nature) has multiple parts arranged for a purpose
  3. Therefore the eye (and other things in nature) must be designed
  4. Anything that is designed has a designer
  5. Therefore, the eye (and other things in nature) must have a designer
  6. (This designer is God)

Problem: Evolution by natural selection

One of the biggest challenges to teleological arguments – especially Paley’s watchmaker argument – is Charles Darwin’s theory of evolution by natural selection, published in On the Origin of Species in 1859. It’s a problem for teleological arguments because it shows how the appearance of design – like the many parts of the eye arranged for vision – can emerge naturally without a designer.

The term ‘natural selection’ captures the objection: nature itself, without a mind or deliberate intention, ‘selects’ traits that help organisms survive and reproduce. Over many generations, this process can produce features that look perfectly designed for a function. So, applied to Paley’s example of the eye, natural selection may say it evolved like this:

  • A random mutation produced a light-sensitive protein in a simple organism.
  • This light-sensitive protein gave this simple organism a survival advantage (e.g. avoiding predators).
  • And so this simple organism survived and reproduced, passing on its genes for light-sensitive proteins.
  • Fast forward a million years or so and millions of random mutations result in multicellular organisms that have dedicated cells for detecting light.
  • These cells arrange into a concave shape as this enables the organism to detect the direction the light is coming from.
  • The concave shape deepens into a cup, improving focus.
  • A primitive lens evolves, sharpening the image.
  • Over millions of years, further refinements produce a complex eye capable of detecting shapes, colours, direction, distance, etc.

Crucially, at no point in this story is there any intelligence, plan, or telos guiding this process. It’s not working toward an ultimate goal – it’s just a mindless, gradual accumulation of small changes, where those that improve survival persist and those that don’t disappear. This eventually results in a sophisticated eye that is so well-adapted to its environment that it seems designed.

  • For Aquinas’ 5th way, evolution challenges the claim that “things which lack intelligence” can “act for an end” only because they are directed by a mind.
  • For Hume’s teleological argument, evolution undermines the inference from the “adapting of means to ends” in nature to a designer.
  • And for Paley, evolution shows that having “several parts… framed and put together for a purpose” is not necessarily the hallmark of design his argument says it is.

“What can be more curious than that the hand of a man, formed for grasping, that of a mole for digging, the leg of the horse, the paddle of the porpoise, and the wing of the bat, should all be constructed on the same pattern, and should include the same bones, in the same relative positions?… all these organs, serving for such different purposes, are formed by infinitely numerous modifications… Nothing can be more hopeless than to attempt to explain this similarity of pattern in members of the same class, by utility or by the doctrine of final causes. ”

– Darwin, The Origin of Species

Swinburne’s teleological argument

Traditional teleological arguments focus on examples of order within nature (spatial order). But Richard Swinburne’s version instead focuses on temporal order:

  • Spatial order: Order within nature – like the eye, the heart, or the wings of a bird. Swinburne calls such order regularities of co-presence because the various parts are organised in space in a way that enables something to fulfil a particular function or purpose. However, such order is potentially explained by evolution by natural selection.
  • Temporal order: Order in the laws of nature – like gravity, the speed of light, or the strong nuclear force. Swinburne calls this regularities of succession because events follow consistent and predictable patterns over time. Unlike spatial order, temporal order cannot be explained by evolution, since the laws of nature themselves are the framework within which evolution occurs.

The laws of nature are consistent and predictable rules that govern how the universe works over time. For example, gravity always attracts masses together in a steady and predictable way; the speed of light doesn’t change from one day to the next; the strong nuclear force holds atomic nuclei together without randomly switching off. Nature’s laws are reliable rather than chaotic. Swinburne likens this to the order of notes in a song: just as the notes are arranged in a specific sequence to create a recognisable melody, the events in the universe follow a consistent sequence according to the laws of nature.

And this temporal order needs an explanation. Why is it that the universe behaves in such a stable, law-like way at all, rather than being a random, unpredictable jumble of events? Why do the ‘notes’ of the universe keep playing the same tune, day after day, century after century? This can’t be explained by evolution. It can’t be explained by any scientific explanation because scientific explanations, by their very nature, have to assume these laws in the first place. Science uses the regularities in the laws of nature to explain phenomena – like using gravity to predict the orbit of planets – but it cannot explain why gravity itself exists or why the laws of nature follow consistent patterns rather than being chaotic. In other words, science can describe and work with temporal order, but it cannot explain the existence of temporal order itself.

“Almost all regularities of succession are due to the normal operation of scientific laws. But to say this is simply to say that these regularities are instances of more general regularities. The operation of the most fundamental regularities clearly cannot be given a normal scientific explanation. If their operation is to receive an explanation and not merely to be left as a brute fact, that explanation must therefore be in terms of the rational choice of a free agent.”

– Swinburne, The Argument from Design

If science can’t account for temporal order, Swinburne says there is another option: a personal explanation.

Scientific explanation Personal explanation
Explained in terms of regular scientific laws Explained in terms of the agency of a mind
E.g. the orbits of the planets are explained by the force of gravity E.g. the book exists because the author wrote it

We give personal explanations for things all the time. For example:

  • “the garden is tidy because the gardener decided to tidy it”
  • “Hamlet exists because Shakespeare wrote it”
  • “the cake exists because Maria wanted to make a cake for her friend”

Again, Swinburne says temporal order cannot be explained scientifically – scientific explanations must assume the very order they seek to explain. And so, if the scientific explanation is ruled out, the best explanation for the consistency of the laws of nature is a personal one: the temporal order of the universe exists because of the agency of a mind. And this mind, says Swinburne, is God.

The fine-tuning argument

The fine-tuning argument is regarded by many philosophers as the strongest version of the teleological argument today. Where Swinburne’s teleological argument (above) focuses on the consistency of the laws of nature, the fine-tuning argument focuses on the specific values of the laws of nature. The argument is that the chance of these values resulting in a universe suited for life (such as ours) is so improbable that it cannot be explained by chance – it must be deliberately designed that way. And, again, if there is design there must be a designer: God.

The universe has many fundamental constants – numbers that define the strength of forces, the masses of particles, and other features of the cosmos. If these numbers were even slightly different, life as we know it could not exist. For example:

  • The gravitational constant (G): If it were slightly stronger, stars would burn out too quickly for life to evolve. If slightly weaker, stars wouldn’t form at all.
  • The strong nuclear force: If it were just 2% weaker, atomic nuclei couldn’t hold together; if 2% stronger, nuclear reactions in stars would be unstable.
  • The cosmological constant (Λ): This tiny number controls the expansion of the universe. If it were larger by a factor of 10¹²⁰, the universe would expand too fast for galaxies to form; if slightly smaller, the universe might have collapsed before life could emerge.

These examples show that the universe is finely tuned for life – the constants fall into an extraordinarily narrow range that permits stars, planets, chemistry, and biology to exist.

The probability of all these constants falling into such a life-permitting range by pure chance (without a designer) is incredibly low – if you change these values even slightly, life couldn’t exist. On the other hand, if a designer exists, it’s highly likely that this designer would choose constants like these that enable life to form. In other words, the fact that the universe is so finely tuned for life is much better explained by a designer than pure chance.

Potential response:

The multiverse hypothesis offers a potential explanation for the laws of nature’s seemingly impossible luck without the need for a designer.

If there is an extremely large – or perhaps infinite – number of universes, and each universe has slightly different physical constants, then it’s inevitable that some of these universes will have the right conditions for life. It’s a bit like Hume’s Epicurean hypothesis (above): Given an infinite amount of time, matter will eventually arrange itself into patterns that appear designed, simply due to the sheer number of possible configurations. And similarly, given an infinite number of universes, it’s inevitable that some of these universes will have laws and constants suited to life, simply because the sheer number of universes makes it statistically unavoidable.

For example, let’s say the cosmological constant has only a 1 in 10¹²⁰ chance of having a life-permitting value. If there were 10¹²⁵ separate universes in a multiverse, then the probability that at least one of them has a life-friendly cosmological constant becomes very high:

  • Probability that a single universe does NOT have a life-permitting constant:
    • 1 – 1/10120 ≈ 1 – 10-120
  • Probability that all 10125 universes do NOT have a life-permitting constant:
    • (1 – 10-120)10125
  • Because 10-120 is extremely small, we can use the approximation (1 – p)n ≈ e-np for large n and small p:
    • np = 10125 * 10-120 = 105
  • This gives us a probability that none of these universes contain life of:
    • P(none) ≈ e-105 ≈ 0
  • And so the probability that at least one universe is life-permitting:
    • P(at least one) = 1 – P(none) ≈ 1 – 0 = 1

In other words, even though the chance of a single universe having a life-permitting cosmological constant is astronomically small (1 in 10120), if there are 10125 universes in a multiverse, it is virtually certain (essentially 100%) that at least one universe will support life.

Problem: Is the designer God?

monotheistic conception of GodEven if we accept that teleological arguments prove the universe is designed, Hume argues the designer might not necessarily be God.

God is typically understood to be:

  • a single monotheistic being
  • that’s maximally powerful (omnipotent)
  • and maximally good (omnibenevolent).

But Hume questions whether we can reason from the apparent design of the universe to a designer with these specific attributes.

Firstly, omnipotence. Hume says we cannot conclude from the universe – if it is designed – that this designer is infinitely powerful (i.e. omnipotent) because the design – i.e. the universe – is not infinite:

“First, By this method of reasoning, you renounce all claim to infinity in any of the attributes of the Deity. For, as the cause ought only to be proportioned to the effect, and the effect, so far as it falls under our cognisance, is not infinite; what pretensions have we, upon your suppositions, to ascribe that attribute to the Divine Being?”

– Hume, Dialogues Concerning Natural Religion

In other words, though vast, there is no evidence that the universe is infinitely large and so no reason to conclude that the designer is infinitely powerful, i.e. omnipotent. This designer could just be very powerful but not omnipotent.

Secondly, says Hume, we cannot conclude from the apparent design of the universe that the designer is perfectly good. We might point to some of the examples of spatial disorder and design flaws (above) as evidence that the designer didn’t care to eliminate evil and so is not omnibenevolent. For example, why wouldn’t an omnibenevolent a designer get rid of the droughts and hurricanes that result in death and destruction? Why wouldn’t an omnibenevolent designer design animals and humans so their lives are easier, with less pain?

“a man who follows [the hypothesis of a designer] is able perhaps to assert, or conjecture, that the universe, sometime, arose from something like design: but beyond that position he cannot ascertain one single circumstance; and is left afterwards to fix every point of his theology by the utmost license of fancy and hypothesis. This world, for aught he knows, is very faulty and imperfect, compared to a superior standard; and was only the first rude essay of some infant deity, who afterwards abandoned it, ashamed of his lame performance: it is the work only of some dependent, inferior deity; and is the object of derision to his superiors: it is the production of old age and dotage in some superannuated deity; and ever since his death, has run on at adventures, from the first impulse and active force which it received from him.”

– Hume, Dialogues Concerning Natural Religion

Thirdly, asks Hume, why should we conclude that the designer is a single monotheistic being?

“And what shadow of an argument, continued PHILO, can you produce, from your hypothesis, to prove the unity of the Deity? A great number of men join in building a house or ship, in rearing a city, in framing a commonwealth; why may not several deities combine in contriving and framing a world? This is only so much greater similarity to human affairs. By sharing the work among several, we may so much further limit the attributes of each, and get rid of that extensive power and knowledge, which must be supposed in one deity, and which, according to you, can only serve to weaken the proof of his existence. And if such foolish, such vicious creatures as man, can yet often unite in framing and executing one plan, how much more those deities or demons, whom we may suppose several degrees more perfect!”

– Hume, Dialogues Concerning Natural Religion

In other words, why should we conclude from the design of the universe that the designer is a single being and not a team of designers? That hypothesis is also possible, given what we can observe.

References/further reading:

See also: