Argument from (evolved) design
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 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 I had before given, that for anything I knew, the watch might have always been there. (...) There must have existed, at some time, and at some place or other, an artificer or artificers, who formed [the watch] for the purpose which we find it actually to answer; who comprehended its construction, and designed its use. (...) Every indication of contrivance, every manifestation of design, which existed in the watch, exists in the works of nature; with the difference, on the side of nature, of being greater or more, and that in a degree which exceeds all computation.
– William Paley, Natural Theology (1802)
This is the most famous expression of the “watchmaker analogy”, often used in support of the 'Intelligent Design' “theory” of evolution.
The basic idea is that as we know that certain examples of complexity around us (watches, computers, the faces on Mt. Rushmore) have been designed by intelligent minds we are justified in assuming that examples of complexity in the natural world (the eye, echolocation) were similarly designed.
However, I think that this idea is seriously flawed in its understanding of designed complexity. Concepts such as the watch or computer did not suddenly spring, fully-formed, into the mind of their designer – but are actually as much the result of mutation and natural selection as any biological system. In order to make clear what I mean, I'll provide a rough outline of how I think the modern concept of the watch evolved:
The ancestor of the modern watch was a simple Concept allowing prehistoric man to structure his day more efficiently – probably no more complex than a distinction between earlier, now and later.
The means of replication was language – Man A would express the concept, spreading it to the mind of Man B. During replication, mutations would creep in, partly through errors in communication and partly through the interaction of the Concept with the other concepts found in the mind of Man B.
Some of these mutations would make the Concept less effective, thus making them less useful and (therefore) less memorable and impeding the spread of that variant. Others would make it more effective, thus making it more memorable and useful and increasing the spread of that variant.
Thus, natural selection comes into play – with increasingly complex variants of the Concept vying for a place in the human mind.
Over time, variants of the Concept become increasingly complex and some evolved to take advantage of man's ability to manipulate his environment – leading to the development of increasingly complex timepieces, which, by increasing the exposure to that design, increase the chance of that particular variant spreading into other minds.
Thus, the watch that Paley stumbles across can be seen as a sort of extended phenotype, “designed” to promote the spread of the Concept in the minds of man, and as such would seem to support rather than challenge the concept of evolved complexity.
What do people think?