Here's the Roman philosopher and politician Cicero on intelligent design, c. 44 BC:
Consider again the harmony, unanimity, and unbroken affinity in nature; this will surely compel one and all to express agreement with my case? How could the earth at one time blossom, but then in turn become rigidly barren? How could the approach and departure of the sun at the summer and winter solstices be signalled by a spontaneous transformation in so much of nature? How could the sea-tides and the confined waters in the straits be affected by the rising and setting of the moon? Or the diverse courses of the stars be maintained in the single rotation of the entire heavens? What is certain is that these processes could not take place through harmonious activity in all parts of the universe, unless they were embraced by a single divine, all-pervading, spiritual force. 1
Understanding how the tides could "be affected by the rising and setting of the moon" was a particular problem in western science until Isaac Newton pretty much nailed it — at least the equilibrium theory of the tides — in his monumental Philosophae Naturalis Principia Mathematica (1687), where he showed how the movement of the tides are a combination of the effects of gravity and inertia as manifested in centrifugal force.
Although Newton had asserted in the Principia that "No more causes of natural things should be admitted than are both true and sufficient to explain their phenomena" (Part III, "The System of the World"), he also had ideas about intelligent design. That all the planets of the solar system rotated in the same direction and in approximately the same plane indicated a deliberate act:
[T]he motions which the planets now have could not spring from any natural cause alone, but were impressed by an Intelligent Agent. For since comets descend into the region of our planets and here move all manner of ways, going sometimes the same way with the planets, sometimes the contrary way, and sometimes in crossways, in planes inclined to the plane of the ecliptic and at all kinds of angles, it is plain that there is no natural cause which could determine all the planets, both primary and secondary, to move the same way and in the same plane, without any considerable variations; this must have been the effect of counsel. Nor is there any natural cause which could give the planets those just degrees of velocity, in proportion to their distances from the sun and other central bodies, which are requisite to make them move in such concentric orbits about those bodies. 2
A century later, Pierre-Simon Laplace hypothesized that the planets travel in the same direction and the same plane as a result of the early formation of the solar system, a concept later called the "nebular hypothesis," which remains (in somewhat altered form) the prevailing model.
The writings of Cicero and Newton and many others form the heritage of natural theology: the derivation of proofs of the existence and attributes of a Creator based on natural phenomenon and human reasoning (as opposed to revealed theology based on divine writings). The seeds of natural theology date at least as far back as the Hebrew Bible: “The heavens declare the glory of God; and the firmament sheweth his handywork.” (Psalms 19:1; also see Psalm 8). In the Laws, Plato demonstrates that the natural world proves that the Gods (notice the plural) care about us and guard our interests.
More modern manifestations of natural theology were particularly pervasive in England following the Restoration (1660), perhaps due to the need to find common ground among the Christian religions and avoid the conflicts that had plagued England after the death of Elizabeth in 1603. William Paley's Natural Theology of 1802 is the best known example, but that book is really more of a summing up of ideas from numerous books and other writings dating back to the seventeenth century.
The above quotation from Newton is from a letter he wrote to the Reverend Richard Bentley, who had been chosen to give the first Boyle Lecture in 1692. In his will, scientist Robert Boyle bequeathed funds to establish lectures for “proving the Christian Religion, against notorious Infidels, viz Atheists, Theists, Pagans, Jews and Mahometans, not descending lower to any Controversies, that are among Christians themselves.” 3 The reference to “theists” may seem odd, but at the time the word denoted a person who believed in God but not much else — someone who might today be considered a deist or a non-denominational believer. The mention of “Controversies, that are among Christians themselves” is a reference to the turbulent religious conflicts of seventeenth-century England among Anglicans, Roman Catholics, and Dissenters.
Even by the time Newton wrote to Bentley, natural theology had altered its focus from the heavens to the bodies of living things. This approach is characterized in such books as the Wisdom of God Manifested in the Works of the Creation (1691) by English naturalist and ordained minister John Ray. Ray had done much of his scientific work in describing and classifying species. In this book he showed how form and function in living things were perfectly meshed. Of the human body Ray said
to imagine that such a machine composed of so many parts, to the right form, order and motion whereof such an infinite number of intentions are required, could be made without the contrivance of some wise Agent, must needs be irrational in the highest degree. 4
Natural theology could also get a bit silly: In his Cosmologica Sacra (1701), Nehemiah Grew asserted that the Creator designed the ears of the horse to be turned towards the rear so the horse could hear his human master's commands! 5
Until well into the nineteenth century, criticisms of natural theology were rare. One major exception is David Hume's Dialogues Concerning Natural Religion (1779), which Hume considered so contrary to public feeling that he didn't seek publication during his lifetime, and it was published after he died in 1776. Because Hume wrote this book as a dialogue (undoubtedly inspired by Cicero's Nature of the Gods), it's sometimes hard to extract Hume's real opinion from it. He seems to think that the existence of the universe implies a Creator, but then concludes that it is impossible to discern the actual nature of this Creator — or even that there's only one.
Although not offering a sustained critique of natural theology, evangelical Christians were somewhat wary of it. Too much reliance on natural theology alone could turn men towards deism — at the time a belief that religion should be purged of everything that could not be established through investigation and reason. For these evangelicals, nature could provide support to one's beliefs, but these beliefs must be supplemented by revelation. The alternative is going down the dangerous path of John Locke, Edmund Halley, and Enlightenment philosophes such as Voltaire, Thomas Paine, and Benjamin Franklin:
Some books against Deism fell into my hands; they were said to be the substance of sermons preached at Boyle's Lectures. It happened that they wrought an effect on me quite contrary to what was intended by them; for the arguments of the Deists, which were quoted to be refuted, appeared to me much stronger than the refutations; in short, I soon became a thorough Deist.” (The Autobiography of Benjamin Franklin)
Perhaps the last major gasp of natural theology was the Bridgewater Treatises of the 1830s. Funded by £8000 pounds bequeathed by the eccentric Reverend Francis Henry Egerton, 8th Earl of Bridgewater, the Bridgewater Treatises presented state-of-the-art intelligent design arguments in 8 books spread out over 12 volumes and over 5,000 pages, to which Charles Babbage voluntarily contributed a Ninth Bridgewater Treatise.
The Bridgewater Treatise by the Reverend William Whewell — the 'W' that begins his last name is silent — was entitled Astronomy and General Physics Considered with Reference to Natural Theology (1833) and in Chapter VII Whewell coined the term "nebular hypothesis." Despite Whewell's realization that later discoveries could render earlier design arguments invalid, he marveled, for example, how the length of the year was precisely suited to the cycles of plants and animals:
The length of the year is so determined to be adapted to the constitution of most vegetables; or the construction of vegetables is so adjusted as to be suited to the length which the year really has, and unsuited to a duration longer or shorter by any considerable portion.... Now such an adjustment must surely be accepted as a proof of design, exercised in the formation of the world. Why should the solar year be so long and no longer? or, this being of such a length, why should the vegetable cycle be exactly the same length? Can this be chance? (Chapter 1)
Without some familiarity with the long English heritage of natural theology, it is impossible to understand the context and revolutionary impact of Charles Darwin's Origin of Species (1859). Darwin was well versed in natural theology. Paley was part of the curriculum at Cambridge where Darwin studied. The second sentence of the Introduction of Darwin's book contains a phrase he found in Charles Babbage's Ninth Bridgewater Treatise. Darwin was familiar from his readings and studies of the multitude of ways in which plants and animals are adapted to their surroundings, and he made sure that natural selection would account for all these adaptations. Without the extensive entanglement of science and religion that characterized natural theology, The Origin of Species would have been quite improbable.
In one sense, Darwin merely shifted perspective. Whereas adaptation between living things and their surroundings had previously indicated design on the part of a Creator, Darwin saw adaptation as a natural process resulting from generational variations, differences in survivability, and the passing on of successful traits to one's offspring. It's a perspective shift, but one as profound as that of Copernicus.
Since The Origin of Species, no prudent scientist ever abandons natural explanations of phenomenon of the natural world, even if our knowledge is not sufficient to formulate a complete explanation. Simply attributing something to "intelligent design" is both lazy and cowardly, and the lessons of thousands of years of natural theology is that it is all too easy for us to discern deliberate design where it simply does not exist. Even among non-scientists, few people are rash enough to base a theology on gaps in our scientific knowledge, because our knowledge of the natural world increases almost daily.
Unfortunately, you won't find a speck of this history or perspective in the recent documentary Expelled: No Intelligence Allowed. This is a frighteningly myopic and dishonest film that presents intelligent design as an exciting new concept promoted by some brilliant scientists who are being silenced by the monolith of Darwinian orthodoxy.
But the target of this documentary is not Big Science. The agenda is very clearly to discredit Darwin and evolution through guilt by association. When a documentary is soaked through with black-and-white images of Nazis, concentration camps, and authoritarianist represssion — when a tour of Darwin's Down House is accompanied by the same dark lighting, spooky music, and ominous camera pans as an earlier tour of Dachau — when host Ben Stein deliberately conducts what appears to be (although I fear not) the most moronic interview that Richard Dawkins has ever endured — when a Ben Stein speech about giving intelligent designers a fair chance is intercut with a Reagan speech about the Berlin Wall — you know you're in the presence of filmmakers whose agenda is much broader than academic freedom.
This isn't science, and it surely isn't theology. It's politics, and it's really about what will be taught in the science classrooms of America's public schools.
1Cicero, The Nature of the Gods, translated by P. G. Walsh (Oxford University Press, 1998), Book 2, Section 19 (page 54).
2H. S. Thayer, ed., Newton’s Philosophy of Nature: Selections from His Writings (Hafner Press, 1953), pages 47-48.
3Andrew Pyle, introduction to The Boyle Lectures (1692 – 1732) (University of Bristol, 2000).
4Quoted in Charles Raven, John Ray: Naturalist, second edition (Cambridge University Press, 1950), page 455.
5Richard S. Westfall, Science and Religion in Seventeenth-Century England (University of Michigan Press, 1958), page 62.