"Intelligent design" creationism is the idea that our universe and particularly earthly biology are so complicated that creation by a deity is the only rational explanation. Its proponents claim to be nascent Galileos stifled by an entrenched establishment (as in the movie Expelled). Perhaps ironically, "intelligent design" was the establishment ... 200 years ago. Darwin and his cohort were suckled on its concepts. Yet design as a useful scientific concept wilted beneath the harsh lights of science: logic and evidence.
The watchmaker argument is hallmark of "intelligent design": "If we find a watch there much be a watchmaker." It formed the centerpiece of Natural Theology (1802; Paley 2008) of William Paley (1743–1805). Paley's watch was no mere timepiece. It was a self-replicating automaton, a consortium of machines. He correctly reasoned by analogy with life that an automaton could reproduce without being aware of its existence, its original fabricator, or even the functions of its component parts. He had no need to cherry-pick examples. Life does show a highly ordered complexity that successfully facilitates its reproduction. The appearance of design is ubiquitous; descriptive words for organisms connote it: for example, "body parts", "body plan", "skeletal structure", and even "creature" in its literal meaning.
Natural Theology, despite its name, consists of descriptive natural history that would later fuel Darwin. Scripture makes a cameo appearance only at the end of his book, which in its day served to interest people in science. Today, it documents the worldview of sincere early scientists struggling with meager information and nascent theory. Paley in practice shared more with modern science than with the professional creationists who have resurrected a debased form of his ideas as part of a cynical "Wedge Strategy".
Just who was Paley? His worldview arose from the science and technology of his time: the start of the industrial revolution. Innovators put mechanical energy to beneficial tasks. Anatomists understood human and animal bodies as complex machines with pulleys and levers. Chemistry was becoming a science; anatomists appreciated that life involved complex chemistry of which they were still largely ignorant. Paley overtly eschewed chemistry in his book for this reason.
The major lacuna in science in 1800 was geology. Next to nothing was known about geological time. The only "old earth" theory available to Paley was Buffon's idea that a comet crashed into the sun and ejected the planets as red-hot masses that subsequently cooled. When Paley corresponded with astronomers to obtain an understanding of planetary orbits, he learned that the idea simply does not work; the orbit of an ejected object returns to the surface of the sun rather than to a circular distant orbit (Paley 2008: 206).
What was Paley's attitude towards an old earth? "It is easy to say this; and yet it is still true, that the hypothesis [of gradual biological change over vast periods of time] remains destitute of evidence" (Paley 2008: 227). "[I]f not in a million of years, perhaps in a hundred millions of years, (for theorists, having eternity to dispose of, are never sparing in time,) [for creatures] to acquire wings" (Paley 2008: 224, emphasis in original). Paley made no reference to speculation on the duration of any geological process. Casual application of geology may well lead one to a young earth. In his time it was known that the inland and coastal landforms of England had been shaped during a glaciation period a few thousands of years earlier, so application of that geological knowledge supported the inference of a young earth. Paley's comparison of a stone having always been in a road with a watch requiring manufacture (Paley 2008: 7) and his remarks that the Creator had no "useful purpose" to mould mountains into "Conic Sections" (Paley 2008: 43) reflect his young-earth mindset.
Paley went to much effort toward refuting the evolutionary theory of his time. The ideas of use-and-disuse evolution and goal-driven evolution were prevalent. Paley doubted that there was enough time for them to act, brought up the lack of evidence of ongoing change, and invoked the creationist staple: if pouches are useful to pelicans, why haven't many more birds evolved them (Paley 2008: 227)? His only other alternative to creation was that given "infinite age" the current situation would arise. He astutely surmised that this concept explained nothing. He did recognize observations that became pillars of natural selection, especially that far more young are born than can survive (Paley 2008: 247–50).
Paley devoted a full chapter to comparative anatomy. He began with Arkwright's mill for spinning cotton. By the time of his book, the contraption had evolved into devices for spinning wool, flax, and hemp. Yet Paley did not recognize this progression as an example of descent with radiation and modification. Rather, given the lack of time available for biological change, he credited both Arkwright and the Creator with an "economy" of design where a single invention worked remarkably well for numerous purposes.
Geology became a science shortly after Paley's death, providing the evidence he lacked. James Although Hutton's old-earth geology was published in 1788, John Playfair's popularization Illustrations of the Huttonian Theory of the Earth did not appear until 1802 along with Paley's work. The Geological Society of London was founded after Paley's death in 1807. William Smith's geology map gave raise to the paleontological time scale. By the publication of the Origin of Species in 1859, it was patently evident that geological time is vast and that the fossil record shows a sequence of increasingly modern forms, with a lot of extinctions on the way. The evolution of vertebrates from a common ancestor with a backbone explained their obvious similarities. We do not find unworkable organisms for the simple reason that they would not emerge in the first place and would die out if they did. The rapid change of domestic animals and plants by artificial selection provided analogy to the slower change by natural selection.
After Darwin, geologists and biologists abandoned recourse to divinity and the search for higher purposes as unproductive. Any conceivable observation can be attributed to divine intervention and, like saying the present state of affairs will arise given infinite time, nothing is actually explained. Yet the implications of the mother of all sampling biases did not sink in until the space-age interest in astrobiology. We have to be here to observe. No event incompatible with our collective or your personal existence can have occurred. Philosophers of science call this concept the weak anthropic principle. As a successful wide-ranging species, we see the illusion of providence; personally we experience the illusion of miracles if we survive in especially trying circumstances.
Several of Paley's providence arguments can be turned into still unresolved "rare earth" or "rare universe" arguments, especially in his chapters on astronomy and the elements. The earth's orbit is nearly circular and the mild and stable tilt of its axis gives rise to modest seasons. There are no giant planets near the sun that would make its orbit unstable. There is the right amount of water to get oceans and dry land. Water has properties that make it an excellent biological fluid. Newton's laws and physics in general work out so that planetary orbits can be stable.
There is no way that the earth and its inhabitants in their present state could have been formed in a few thousand years by natural processes, so in order to insist on a young earth, it is necessary to have recourse to the supernatural. Paley (2008: 26–7) allowed supernatural processes for creation but rejected overt deviations from the general laws of physics. This history is a prime example how the unscientific practices of invoking divine intervention and seeking purposes in nature were phased out and how science consigns constructs into the dustbin as new evidence becomes available. Paley in part acted like a modern scientist. He gathered the available data and consulted with experts. He willingly and correctly examined Buffon's hypothesis with physics, not Scripture. His young-earth constructs arose from the lack of evidence for an old earth.
There is a good analogy between Aristotle's unchanging geocentric heavens and Paley's young earth populated by unchanging species. Both constructs started with valid observations: we all sense terra firma and well functioning organisms in our daily lives. Paley's examples of designed contrivances became Darwin's examples of evolutionary adaptation, much as well-documented geocentric epicycles were transformed into heliocentric orbits. Galileo pointed out forcefully throughout the Dialogue that Aristotle lacked evidence, including the appearance of "new" stars that pointed to changeable heavens and telescopic observations that supported the Copernican system; Paley lacked our vast knowledge of geology and molecular biology. With regard to K–12 instruction, we do not hide the existence of geocentric astronomy from students; we should not conceal that biology began as a study of design and a search for God's plan. The movement away from that emphasis was not a matter of rejecting theological positions as much as it was embracing scientific ones.