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 anything I knew to the contrary it had lain there forever; nor would it, perhaps, be very easy to show the absurdity of this answer.
But suppose I 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 given, that for anything 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 admissible in that second case as in the first?
For this reason, and for no other, namely, 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, or placed in any other manner or in any other order than that in which they are placed, either no motion at all would have carried on in the machine, or none which would have answered the use that is now served by it. (William Paley, Natural Theology, p. 1)
William Paley’s famous argument for creation by a designer consists of two distinct arguments joined together:
Artefacts like watches and living organisms like eyes have special functions. Watches to tell the time; various kinds of eyes to see in various types of environments: “each such entity exists because of its function” (p. 42);
Such functionality implies a designer both conscious and intelligent.
Biologists accept the first argument.
The second proposition seems right given the axiom that a cause must precede every effect. The effect is the ability to see. It must therefore follow that the eye was caused to exist for this specific function. In other words we have a teleological argument for the existence of eyes. They appeared for the purpose of enabling sight.
According to Paley there are only two alternatives. A complex organism, such the eye, must have come about either by
