Teleological arguments get that name from the ancient Greek word telos, meaning end, goal, or purpose. And teleological arguments argue that there are examples of telos in nature – examples of purpose and design – which suggest the existence of a designer who made them this way: God.
For example, the eye: it’s got many different parts working together for the purpose of vision. The cornea lets light in and starts focusing it. The muscles around the pupil adjust to control how much light gets through. The lens changes shape depending on how far away something is, helping you see clearly. All of these parts are arranged in a seemingly purposeful way to produce vision.
This kind of purposeful arrangement may seem similar to man-made things, like a watch. A watch has gears, springs, hands, and many different components that work together to tell the time. And teleological arguments argue that the similarities go further: The watch and the eye are also similar in that they both have a designer. That’s the crux of classic teleological arguments.
But not all teleological arguments are the same. Two of the most famous ones – by David Hume and William Paley – take slightly different forms. Hume offers an analogical argument, while Paley’s is more deductive. This post explains the difference.
Hume’s teleological argument (an argument by analogy)
In Dialogues Concerning Natural Religion, David Hume presents the teleological argument through a fictional character named 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 (emphasis added)
This version of the argument works by analogy – that because A and B are similar in some ways, they’re probably the same 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. This isn’t conclusive proof – it’s of course possible that your friend hates the movies you do even if they like the same art and music you do – but if two things are similar in most ways then it’s good inductive evidence that they’re going to be similar in other ways.
So with that in mind, here’s the basic structure of Hume’s teleological argument:
- There is an ‘adapting of means to ends’ in human machines (e.g. the parts of a watch to tell time)
- There is an ‘adapting of means to ends’ in the universe (e.g. the parts of the heart to pump blood, and the heart within the body to maintain life, and so on)
- Similar effects typically have similar causes
- The cause of human designs are minds
- So, by analogy, the cause of the universe is probably also be a mind
Hume’s objections to the analogy
Hume’s teleological argument above was made as part of a wider dialogue which includes responses to it. Through the character Philo, Hume points out that arguments from analogy are only as strong as the similarities between the two things being compared – in this case man-made designs and nature:
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
For example:
- A lion is fluffy like a cat
- Cats make good pets
- So, by analogy, lions probably make good pets too
This is another argument from analogy – that because cats and lions are similar in one way, they’re similar in another way too – but the conclusion is clearly false. There are a bunch of important differences between cats and lions – such as size, strength, and behaviour – that mean the analogy breaks down under closer investigation.
Similarly, Philo points out a bunch of differences between man-made designs and nature, weakening the analogy:
No experience of a designer:
We have direct experience of people designing things like watches and houses. But we’ve never actually seen a planet or an eye being designed by some cosmic engineer. What we have observed in nature are processes like growth, reproduction, and evolution-like change – what Philo calls “generation and vegetation.” So if anything, those are the kinds of causes we should expect behind natural complexity – not an intelligent designer.
Generalising from parts to whole:
The argument often focuses on a few especially impressive examples, like the eye or the wings of a bird. But it ignores all the messy, purposeless, or chaotic parts of the universe – like pointless rocks floating in deep space or massive stretches of nothingness. If you’re going to make a general claim about the whole universe being designed, you can’t just cherry-pick the bits that work and seem designed whilst ignoring the bits that don’t seem very designed.
Lack of obvious purpose:
Human machines (e.g. watches and cars) obviously have a designer and a purpose. But biological things (e.g. an animal or a plant, such as a cabbage) do not have an obvious purpose or designer.
Again, arguments from analogy are only as strong as the similarities between the two things being compared. And so these differences weaken the jump from man-made items being designed to the whole universe being designed.
Paley’s teleological argument (a deductive argument)
Writing a few decades after Hume, Paley offers a version of the teleological argument that at first sounds very similar:
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? 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 different 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.
– Paley, Natural Theology (emphasis added)
However, where Hume’s argument take the format of an analogy, Paley’s can be interpreted differently. He doesn’t say this explicitly, but his argument here can be interpreted as a deductive argument instead:
- Anything that has several parts arranged for a purpose (e.g. a watch) is designed
- The eye (and other things in nature) has several parts arranged for a purpose
- Therefore the eye (and other things in nature) is designed
- Anything that is designed must have a designer
- Therefore the eye (and other things in nature) has a designer
- (This designer is God)
So Paley isn’t just saying “the eye is like a watch.” He’s saying the same reasoning we use to infer design in a watch can and should be applied directly to the eye. The watch is just a tool to help us understand how to reason about design, and this reasoning tells us that there is a key property of design – having “several parts are framed and put together for a purpose” – and that anything with this property must be designed.
In short, while Hume says, “You can’t argue from a watch to the world,” Paley replies, “I’m not. I’m arguing from the logic of design detection itself, which applies just as clearly to the eye as to the watch.”
Interpreted this way, Paley’s argument avoids Hume’s criticism of the analogy above:
Weaknesses in the analogy:
Paley’s argument doesn’t rest on analogy in the way Hume targets. He’s not saying the universe is like a watch, so it probably has a designer too. Instead, he’s saying the same inference procedure that leads us to conclude a watch has a designer can be directly applied to natural objects like the eye. The watch serves as a clear-cut example of design reasoning -not as a basis for analogical comparison.
So, the strength of the argument doesn’t depend on how similar natural things are to man-made ones, but on whether certain features (like purposeful arrangement) reliably indicate design – regardless of where they appear.
Generalising from parts to whole:
Hume says the design argument cherry-picks examples that seem ordered, while ignoring all the randomness in nature. But Paley avoids this because he’s not making a generalisation from parts to the whole universe. Instead, he’s arguing that this feature – “several parts are framed and put together for a purpose” – on its own proves intentional design every time it is found:
“If there were but one watch in the world, it would not be less certain that it had a maker… Of this point, each machine is a proof, independently of all the rest. So it is with the evidences of a Divine agency. The proof is not a conclusion which lies at the end of a chain of reasoning, of which chain each instance of contrivance is only a link, and of which, if one link fail, the whole falls; but it is an argument separately supplied by every separate example. An error in stating an example, affects only that example. The argument is cumulative, in the fullest sense of that term. The eye proves it without the ear; the ear without the eye. The proof in each example is complete”
– Paley, Natural Theology
In other words, each instance of apparent design stands on its own. The argument doesn’t collapse if some parts of nature look disordered or purposeless.
Lack of obvious purpose:
Hume questions whether biological entities like a cabbage have any obvious function or purpose in the way a watch or a car clearly does. But, for Paley, purpose isn’t always about utility to humans – it’s about whether the parts of something are arranged and work together in a way that suggests design.
The eye, for example, has a highly coordinated structure that enables vision. The arrangement of its parts clearly serves an end. So, while something like a cabbage might seem less obviously purposeful, many natural entities (especially organs and biological systems) do exhibit this kind of end-directed structure. That’s what matters for Paley – not how useful they are to us, but whether they appear shaped for a function.
No experience of a designer:
Hume argues that we’ve seen humans designing things, but not eyes or planets being designed and so the analogy fails. But Paley isn’t relying on direct experience of divine creation. His claim is that certain patterns (like coordinated parts serving a purpose) are reliable signs of intentional design, regardless of whether we’ve observed the designer at work.
We don’t need to see the designer of a watch to know it had one. The same goes for natural objects. Paley is offering an inference to the best explanation: the presence of design-like properties makes intentional design the most reasonable conclusion, even if the designer is unseen.
Hume vs. Paley and beyond
Both Hume and Paley were writing before a major turning point in science: Charles Darwin’s theory of evolution by natural selection. The theory of evolution pulls the rug out from under both arguments because it shows how…
- “The curious adapting of means to ends” as Hume says, and
- how ““several parts” in nature can be “framed and put together for a purpose” in Paley’s terms
…can emerge in nature without invoking a designer at all. So, whether the argument is analogical (Hume) or deductive (Paley), it’s a big problem for both teleological arguments.
Since Darwin, modern teleological arguments often point to order beyond what can be found within nature – such as eyes, wings, hearts, and other biological features that can be explained via evolution – to order and purpose in the laws of nature, such as gravity and electromagnetism. An example of this is Richard Swinburne’s teleological argument, which calls such order in the laws of nature temporal, rather than spatial, order. Another example of this would be the fine-tuning argument. These arguments avoid the evolution objection because the laws of nature, like gravity, don’t reproduce and evolve like biological entities do.