AQA A-Level Religious Studies

The design argument (the teleological argument) moves from features of the world to the existence of a designer. It is an a posteriori argument, because its starting point is observation, and it is inductive, so its conclusion is made probable by the evidence, not guaranteed by it. William Paley set out its best-known form in Natural Theology (1802), and David Hume's criticisms, written in the Dialogues Concerning Natural Religion (published 1779, after his death), are the standard reply.

Paley's analogical argument

Paley begins with a thought experiment. Walking across a heath, you might trip over a stone and wonder how it came to be there; you would be content to say it had always been there. If you found a watch, you could not say that, because on inspection you would see that its parts are fitted together for a purpose: the spring drives the wheels, the wheels turn the hands, and the glass lets you see the dial. The parts are made and arranged so that the watch tells the time, and if they were shaped or ordered differently it would either fail or do nothing useful. From this you would conclude that the watch had a maker who understood its construction and designed it for its use.

Paley then draws the analogy. The universe, and above all living things, show the same marks that the watch does, only on a far larger scale and with far greater skill. His favourite example was the human eye, which he compared with a telescope: both are built to focus light on a surface, and the eye is so well adapted to this that it points to a designer in the way the telescope points to an optician. He also pointed to the regular motions of the planets under the laws of gravity, to the structure of the human body, and to the adaptation of animals to their surroundings. The argument can be set out in steps.

1. Things such as watches show purpose, complexity and the fitting of parts to an end.
2. Such things are always the product of an intelligent designer.
3. The universe and living things show purpose, complexity and the fitting of parts to an end, on a vastly greater scale.
4. So the universe has an intelligent designer, and that designer must be far greater than any human, and is God.

Paley's discussion contains further points. A watch that sometimes goes wrong, or whose workings we only partly understand, would still be recognised as designed, so the existence of imperfection or of things we do not understand does not destroy the argument. And he held that a watch able to produce other watches would only make the skill of its maker more impressive, which answers in advance the objection that nature reproduces itself.

The argument rests on three features that Paley takes to be evidence of design: purpose (the parts of the thing serve an end), complexity (many parts working together) and regularity (the world behaves in a predictable and ordered way, as in the planets' paths). The regularity of the universe matters as a separate point, because order of that kind is what a designer would be expected to impose.

Hume's criticisms

Hume's Dialogues are a conversation between three characters, and the sceptic, Philo, voices the main objections to the design argument; it is usual to take Philo as close to Hume's own view, though Hume does not say so. The objections run as follows.

The analogy is weak

An argument from analogy is only as strong as the likeness between the two things compared. Hume has Philo argue that the universe is not very like a watch or a house. It is at least as like an animal or a vegetable, which grows and reproduces itself without a designer in the usual sense, so the analogy could as easily support the conclusion that the universe was generated or grew. The more the two things differ, the less confident the inference that they have similar causes.

The universe is unique

We reason about the causes of objects because we have seen many of them made and have seen who made them. We have experience of watches being made, but not of universes being made, and we have only one universe to examine. With no comparison class, we cannot say what a universe caused by design would look like, as against one that was not.

The designer need not be the God of classical theism

Even if the argument showed some designer, Hume has Philo point out that it would not show that the designer is one, all-powerful, all-knowing, perfectly good or eternal. We infer a cause only as great as is needed to produce the effect. A ship is the work of many shipbuilders, so the world could be the work of a committee of lesser gods. A designer could be a young or unskilled deity, a first and imperfect attempt that a better one improved on, or a being that has since died. Philo makes the further point that the world contains much evil and apparent waste, and these hardly suggest a perfect designer.

The regress

If the order of the universe needs a designer, the designer's own mind is orderly and complex and so seems to need an explanation too, and the question of who designed the designer has no end. Hume suggests that we might as well stop at the universe itself and say that its order is just there.

Order may arise by chance

Philo proposes what is sometimes called the Epicurean hypothesis. If the universe were made of a finite number of particles moving at random for an infinite time, every possible arrangement would eventually arise, and one of them would be a stable and orderly one. Order of the sort we see would then be no surprise, and what looks like design would be the settling of matter into a self-sustaining form. Hume does not endorse this as true; his point is that the design hypothesis is not the only way to explain order.

Evaluating the argument

Darwin's theory of evolution by natural selection, published in 1859, is the most serious scientific rival to Paley's argument. Natural selection explains how complex structures such as the eye can arise by small stages from simpler ones, because variations that help an organism survive and breed are passed on, so adaptation to an environment appears without foresight. Richard Dawkins's The Blind Watchmaker (1986) argues that this removes the need for a designer. A religious reply is that evolution can itself be understood as the means by which God works, and that the laws of nature which allow life to evolve, and the fact that the universe permits life at all, need explaining; F. R. Tennant argued along these lines in the early twentieth century, and the argument from the fine-tuning of physical constants has been developed by modern writers such as Richard Swinburne.

Several other points come up in discussion of the argument.

• Strengths: it begins from something everyone can observe; it is easy to grasp; it can be supported by scientific discoveries of order; an analogy of this type is a normal way of reasoning in everyday life.
• Weaknesses: it is an inductive argument, so it can at best make God probable; the analogy with a human artefact is open to Hume's objections; it does not by itself reach a God who is the creator of everything, and the existence of evil and suffering seems to count against a benevolent designer.
• Status: few defenders claim that it is a proof in the sense of a conclusive demonstration. Its value for faith is usually taken to be as evidence that makes belief reasonable, which a believer may find confirms what they already hold, and not as something that can compel agreement.