William Paley, answered from the texts and cited to the page.
The inference begins simply enough. Suppose you cross a heath and your foot strikes a stone; you ask how it came to be there, and the answer — that it has lain there forever — may satisfy you well enough. But suppose instead you find a watch upon the ground. The same answer will not serve, and the reason is exact: when you examine the watch, you perceive that its several parts are framed and put together for a purpose — 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.1
The stone showed no such thing. The watch does, and that difference is everything. The parts I enumerate because the weight of the argument is in the enumeration, not in the summary. A cylindrical box containing a coiled elastic spring; a flexible chain communicating the action of that spring to the fusee; a series of wheels whose teeth conduct the motion onward, regulating it by their size and shape until an index passes over a given space in a given time; brass chosen for the wheels to resist rust, steel for the springs because no other metal is so elastic, glass placed over the face because nothing opaque would serve.2
Every choice answers to a purpose, and the purposes conspire to a single end. From this, the inference is — as I put it, and I chose the word deliberately — inevitable: the watch must have had a maker, an artificer who comprehended its construction and designed its use. Now, the objection most commonly raised is that this proves too little unless contrivance is everywhere, and that a single instance might be dismissed as coincidence.
My reply is in chapter six of Natural Theology, and it runs the other way from what the objector expects: were there no example in the world of contrivance except that of the eye, it would be alone sufficient to support the conclusion, because it could not be accounted for by any other supposition that did not contradict all the principles we possess of knowledge.3
The argument does not require universality to be valid; one clear instance of means adapted to an end, fully understood, is enough. But in fact the instances are not one — they are everywhere, and the book spends twenty chapters saying so. A second objection, more interesting, is the one about reproduction. Suppose the watch, in the course of its movements, produced another watch like itself — a mechanism within it, a system of lathes and files, evidently calculated for that purpose.4
Does this dissolve the need for a maker? It does not. The watch before us may in some sense be called the maker of the watch that follows, but it is so in a very different sense from that in which a carpenter is the maker of a chair — the author of its contrivance, the cause of the relation of its parts to their use.5 The first watch was no such cause to the second.
It transmitted the mechanism; it did not originate it. The further move — that an infinite series of such watches removes the question altogether — is the one I press hardest against, and the answer is in the nature of what we are explaining. Contrivance, design, the suitableness of means to an end: these are not explained by multiplying the number of things that exhibit them.6
Here is contrivance, but no contriver; proofs of design, but no designer — and that deficit is not remedied by extending the series to infinity, any more than a chain of copies establishes the original author of the thing copied.
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 dayNatural Theology
the wheels are made of brass in order to keep them from rust; the springs of steel, no other metal being so elastic; that over the face of the watch there is placed a glass, a material employed in no other part of the work, but in the room of which, if there had been any other than a transparent substance, the hour could not be seen without opening the caseNatural Theology
Were there no example in the world, of contrivance, except that of the eye, it would be alone sufficient to support the conclusion which we draw from it, as to the necessity of an intelligent Creator. It could never be got rid of; because it could not be accounted for by any other supposition, which did not contradict all the principles we possess of knowledgeNatural Theology
the person who found the watch, should, after some time, discover that, in addition to all the properties which he had hitherto observed in it, it possessed the unexpected property of producing, in the course of its movement, another watch like itself (the thing is conceivable); that it contained within it a mechanism, a system of parts, a mould for instance, or a complex adjustment of lathes, files, and other tools, evidently and separately calculated for this purposeNatural Theology
though the watch before him were, in some sense, the maker of the watch, which was fabricated in the course of its movements, yet it was in a very different sense from that, in which a carpenter, for instance, is the maker of a chair; the author of its contrivance, the cause of the relation of its parts to their useNatural Theology
the question which irresistibly presses upon our thoughts, is, whence this contrivance and design? The thing required is the intending mind, the adapting hand, the intelligence by which that hand was directed. This question, this demand, is not shaken off, by increasing a number or succession of substances, destitute of these properties; nor the more, by increasing that number to infinityNatural Theology