Natural Theology

William Paley (1743–1805) was an Anglican clergyman and successful writer whose Principles of Moral Philosophy (1785) and Natural Theology (1802) were widely read, especially by students, well into the nineteenth century. The central argument of Natural Theology was that living things are comparable to mechanical contrivances, such as watches; and just as from a mechanical contrivance we infer a human designer, so, by analogy, from natural contrivances we should infer a divine designer (see Addinall; Brooke, 2003; Nuovo). The opening paragraph of Paley's Natural Theology, quoted below, set the tone for the central analogy of the book. The title of Richard Dawkins's 1988 book, The Blind Watchmaker, alludes to this argument by suggesting that blind Darwinian processes of variation and natural selection have replaced Paley's divine watchmaker.

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 show the absurdity of this answer. But suppose I had found a watch upon the ground, and it should be inquired 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.… This mechanism being observed (it requires indeed an examination of the instrument, and perhaps some previous knowledge of the subject, to perceive and understand it; but being once, as we have said, observed and understood), 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.