Catholic Daily Mass Take up and read

The Argument from Design

From the order and apparent purpose of the natural world to a designing intelligence. Its most famous form is Paley's watch (1802); Aquinas's Fifth Way is a distinct, subtler version; the objections of Hume (1779) and Darwin (1859) are hosted here in full.

Premises & Hinge

The Argument

The numbered form is ours, after Paley's Natural Theology (1802) and Aquinas's Fifth Way; cf. the SEP, "Teleological Arguments for God's Existence" — the words themselves are the philosophers', below.

  1. P1 The natural world shows intricate order and apparent purpose — parts arranged as if for an end.
  2. P2 Such order and apparent purpose are reliable signs of a designing intelligence. the hinge
  3. P3 The order in nature far exceeds that of any human artifact, such as a watch.
  4. Therefore nature is the work of a designing intelligence — which we call God.

The sources

The Argument Saint Thomas Aquinas 1274
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.

Source — Saint Thomas Aquinas, Summa Theologica I, q. 2, a. 3 — the Fifth Way

The Argument William Paley 1802
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 … But suppose I had found a watch upon the ground … 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 … 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.

Source — William Paley, Natural Theology, ch. 1 — the watch upon the heath

Objection David Hume 1779
The world plainly resembles more an animal or a vegetable, than it does a watch or a knitting-loom. Its cause, therefore, it is more probable, resembles the cause of the former. The cause of the former is generation or vegetation. The cause, therefore, of the world, we may infer to be something similar or analogous to generation or vegetation.

Source — David Hume, Dialogues Concerning Natural Religion, Part VII (Philo)

Objection Charles Darwin 1859
To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree. Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist … then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real.

Source — Charles Darwin, On the Origin of Species, ch. 6 — organs of extreme perfection

Argument hinges on:

The inference from design to a designer Such order and apparent purpose are reliable signs of a designing intelligence. What does that mean?
The library's note

Paley's example is the heart of it. Walking across a heath, you kick a stone and think nothing of it — for all you know it has lain there forever. But if you found a watch, you could not shrug the same way: its wheels and springs are so precisely fitted to measure out the hour that you would conclude, at once, that someone made it. The inference is not from how the watch looks, but from means arranged toward an end.

Now, the argument says, turn to a living eye — its lens focusing light, its iris adjusting to brightness — and you find contrivance beyond any watch. If the watch demands a watchmaker, how much more the eye?

The hinge is that step: that arrangement-toward-an-end is a reliable mark of a mind. Two very different challenges press on it. Hume argued — decades before Paley — that the analogy is weak: the universe resembles a growing plant or animal as much as a made machine, and we have no experience of worlds being manufactured to compare it against. Darwin then offered a rival cause for the very contrivances Paley pointed to: natural selection, working on tiny inherited variations over vast stretches of time, can build an eye by slow degrees, with no foresight at all. Whether apparent design still points beyond nature once natural selection is on the table — or whether the deeper order that makes selection itself possible does — is where the modern form of the argument, from "fine-tuning," now lives.

Written for this library — not a quoted source. It reports how the premise is argued and answered; the philosophers' own words are above.

Where it leads

Accept that apparent design is a reliable sign of a designer, and this argument leads to a designing intelligence behind the order of nature.

Beyond the public domain

The modern revivals and their critics are under copyright, so we don't host them — the reading doesn't stop at the public-domain record. Follow it at the sources:

Stanford Encyclopedia of Philosophy — Teleological Arguments Robin Collins & Richard Swinburne — the fine-tuning argument Richard Dawkins, The Blind Watchmaker (1986) — the reply to Paley

You have read the premise and the objection. The library draws no conclusion. The cost of accepting or denying it is not yet set out.