Is purposive, intelligent design detectable by the scientific investigation of nature? Surely, the answer to this question is an unambiguous “yes.”I discuss the topic of this essay in some detail in my new book, On Purpose, about to be published by Princeton University Press.

If we learned anything from Archdeacon William Paley on natural theology, if you come across a watch in the wilderness, you can be damn sure that it didn’t just happen.William Paley, Natural Theology (Collected Works: IV) (London: Rivington, [1802] 1819). Someone, somewhere, thought it up and made it. Is intelligent design detectable? Oh my goodness yes!

So that’s the answer to that question. But before we pack up and go off and have a beer, think for a moment about another question lurking behind this one. Is Intelligent Design that was not produced by humans (or other natural things we encounter, like beavers building dams) detectable? Is Intelligent Design produced by spiritualThe issue I take it is not whether the evidence is there and detectable, but whether we should interpret it in the way that we do. beings like the Christian God detectable by science? Again, surely, the answer is an unambiguous yes. If God set out to plan and make an eye, and then did just that, don’t we have something where we can detect him at work? The eye didn’t just happen, any more than the watch did.

So, if these questions are so easy to answer, what is at stake here? The issue I take it is not whether the evidence is there and detectable, but whether we should interpret it in the way that we do. Does the empirical evidence press on us an Intelligent Designer? We are ruling out a human (or animal) intelligent designer and, I presume, a grad student on Andromeda who is using Planet Earth as a case study for its (let’s not assume that our grad student is a boy or girl) dissertation. “Methodology: On Planet Alpha I made humans without eyes and on Planet Earth I made humans with eyes and compared the results over a ten-million-year study.” From my experience of graduate students, the time scale has the ring of authenticity.

Evaluating the Artifacts

We steer into more familiar grounds. Why should we think the eye was designed? Well, because it looks like an artifact and we know that artifacts are designed. No other answer will do. Now we do have a question with bite. Does the eye really look like an artifact? We also have a literature to draw on, most notably the Dialogues of David Hume.David Hume, ed. Martin Bell, Dialogues Concerning Natural Religion, (London: Penguin, [1779] 1990). We might want to say that the eye does look like an artifact but how good an artifact is another matter. There are lots of things about eyes that are not as well designed as they might be, starting with all of that inverted retinal image stuff. We might want to say that there is a designer, but hardly an intelligent designer. And that worry gets greater when we think of all of those things that don’t work that well. In my candid opinion, speaking as an older male, the intelligence that designed the male urogenital system should be taken out and shot. At least, it should be made to get up and go to the bathroom ten times a night rather than me. And as for the prostate, let’s not go there.George Christopher Williams, Adaptation and Natural Selection (Princeton: Princeton University Press, 1966).

On top of this, we might have design, but are we comfortable with a squad of designers as at General Motors rather than one individual? Are we happy with a slew of planets with beings with very poor eyes, as our designer learnt the trade and got better and better at it and made better and better artifacts? Just think back thirty years or so to the earliest laptops and compare those with the ones that we have today.Something had to produce the eye, blind chance could not, an Intelligent Designer could, so in the absence of any other solution the Intelligent Designer has it. Or, although I won’t be around, the laptops of today with those of thirty years hence—if indeed, anyone bothers with laptops around midcentury. So even if you think there is something detectable—and like Hume (in the end) I am inclined to say that the evidence is that there is something—eyes don’t just happen—be careful about what you wish for. It might not be the kind of Intelligent Design that you have in mind.

Perhaps all of this talk about analogy is the wrong way to go. There is another strategy you might take and Hume might have had this in mind at the end of the Dialogues. Something had to produce the eye, blind chance could not, an Intelligent Designer could, so in the absence of any other solution the Intelligent Designer has it. This is the kind of argument that Charles Sanders Peirce called “abduction” and that is known today as “inference to the best explanation.” It is the argument favored by Sherlock Holmes, in The Sign of the Four. “How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?” You may not much like it, particularly if your name is Richard Dawkins, but that is the way you must go. There was Intelligent Design.

The Origin of an Alternative

Of course, this argument depends crucially on there being no alternatives. And here’s the rub! After the Origin of Species, published in 1859, there is an alternative. Evolution through natural selection:

Let it be borne in mind in what an endless number of strange peculiarities our domestic productions, and, in a lesser degree, those under nature, vary; and how strong the hereditary tendency is. Under domestication, it may be truly said that the whole organisation becomes in some degree plastic. Let it be borne in mind how infinitely complex and close-fitting are the mutual relations of all organic beings to each other and to their physical conditions of life. Can it, then, be thought improbable, seeing that variations useful to man have undoubtedly occurred, that other variations useful in some way to each being in the great and complex battle of life, should sometimes occur in the course of thousands of generations? If such do occur, can we doubt (remembering that many more individuals are born than can possibly survive) that individuals having any advantage, however slight, over others, would have the best chance of surviving and of procreating their kind? On the other hand, we may feel sure that any variation in the least degree injurious would be rigidly destroyed. This preservation of favourable variations and the rejection of injurious variations, I call Natural Selection.Charles Darwin, On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life (London: John Murray, 1859), 80-81.

Note that natural selection doesn’t just cause change, but change of a particular kind. It produces adaptations, design-like characteristics, like the eye. Change is not higgledy-piggledy, but as if contrived:

How have all those exquisite adaptations of one part of the organisation to another part, and to the conditions of life, and of one distinct organic being to another being, been perfected? We see these beautiful co-adaptations most plainly in the woodpecker and missletoe; and only a little less plainly in the humblest parasite which clings to the hairs of a quadruped or feathers of a bird; in the structure of the beetle which dives through the water; in the plumed seed which is wafted by the gentlest breeze; in short, we see beautiful adaptations everywhere and in every part of the organic world.Ibid., 60-61.

We all know that, since the Origin, there have been horrendous numbers of arguments about whether natural selection can really do the job.Michael Ruse, Monad to Man: The Concept of Progress in Evolutionary Biology (Cambridge: Harvard University Press, 1996). In the early years, in the scientific world, some always thought it could, particularly those working on fast breeding organisms like insects. But others, like Darwin’s great supporter Thomas Henry Huxley, were doubtful. However, with the coming of genetics in the twentieth-century—first Mendelian and then molecular—confidence grew and grew and regular professional evolutionary biologists are convinced that selection can do the job.Michael Ruse, Darwinism and its Discontents (Cambridge: Cambridge University Press, 2006). No need for an Intelligent Designer. Sorry.

Responding to Natural Selection

There are two ways the argument can go at this point. One is to keep up the discussion about whether natural selection is adequate. This I take it is the point of attack of people like Michael Behe, who argue that selection is not adequate and things like the bacterialI will note the surprising fact that not only believers seem sympathetic to the Intelligent Design cause but, paradoxically, non-believers, especially my fellow philosophers. flagellum require some kind of divine intervention.Michael J. Behe, Darwin’s Black Box: The Biochemical Challenge to Evolution (New York: Free Press, 1996). I take it that it is the point of defense of people like Kenneth Miller, who argue that selection is quite adequate thank you, and that the bacterial flagellum can be given a naturalistic explanation in terms of Darwinian selection.Kenneth R. Miller, Finding Darwin’s God (New York: Harper and Row, 1999). I won’t say much about this here because obviously minds are set and no one is going to change.William A. Dembski and Michael Ruse, eds., Debating Design: Darwin to DNA (Cambridge: Cambridge University Press, 2004).

I will note the surprising fact that not only believers seem sympathetic to the Intelligent Design cause but, paradoxically, non-believers, especially my fellow philosophers. They seem to believe in some kind of natural world spirit, perhaps the laws of physics and chemistry, at times almost in a Spinozistic pantheistic sort of way. For instance, Duke University colleagues, biologist Daniel McShea and philosopher Robert Brandon, have come up with—a term for production that covers “invents” as well as “discovers”—what they proudly call “biology’s first law.” Named the “zero-force evolutionary law” or ZFEL, its general formulation runs:

In any evolutionary system in which there is variation and heredity, there is a tendency for diversity and complexity to increase, one that is always present but that may be opposed or augmented by natural selection, other forces, or constraints acting on diversity or complexity.Daniel W. McShea and Robert N. Brandon, Biology’s First Law: The Tendency for Diversity and Complexity to Increase in Evolutionary Systems (Chicago: University of Chicago Press, 2010).

This seems at least a rival to natural selection and as you can imagine about as credible to regular Darwinian evolutionists as the tooth fairy.

The Finch & the Cardinal

The other way that the argument can go is simply to accept natural selection and its power and wonder why this would at all trouble belief in an Intelligent Designer. This seems to have been Darwin’s position, at least when he wrote the Origin. Significantly the following passage was unchanged through to the sixth edition of 1872, by which time Darwin was speaking of himself as an agnostic:

Authors of the highest eminence seem to be fully satisfied with the view that each species has been independently created. To my mind it accords better with what we know of the laws impressed on matter by the Creator, that the production and extinction of the past and present inhabitants of the world should have been due to secondary causes, like those determining the birth and death of the individual. When I view all beings not as special creations, but as the lineal descendants of some few beings which lived long before the first bed of the Silurian system was deposited, they seem to me to become ennobled.Darwin, Origin of the Species, 488-89.

There have always been Christian philosophers and theologians, notably, in the past two or three centuries, Immanuel Kant, Soren Kierkegaard and Karl Barth, who have disliked natural theology. Kant said that he had to get rid of reason to make room for faith.Immanuel Kant, trans. and ed. Allen W. Wood and Paul Guyer, Critique of Pure Reason, (Cambridge: Cambridge University Press, [1787] 1998). If you can prove things, then what is the point of faith? It is not that you don’t appreciate design and its evidence. It is rather that you take this to burnish your view of the Creator, not to prove his existence. John Henry Newman put things rather well and is a good point on which to end this short essay. He was writing to a friend about his classic, The Grammar of Ascent:

I have not insisted on the argument from design, because I am writing for the 19th Century, by which, as represented by its philosophers, design is not admitted as proved. And to tell the truth, though I should not wish to preach on the subject, for 40 years I have been unable to see the logical force of the argument myself. I believe in design because I believe in God; not in a God because I see design. You will say that the 19th Century does not believe in conscience either—true—but then it does not believe in a God at all. Something I must assume, and in assuming conscience I assume what is least to assume, and what most will admit. Half the world knows nothing of the argument from design—and, when you have got it, you do not prove by it the moral attributes of God—except very faintly. Design teaches me power, skill, and goodness, not sanctity, not mercy, not a future judgment, which three are of the essence of religion.John Henry Newman, eds. Charles Stephen Dessain and Thomas Gornall, The Letters and Diaries of John Henry Newman, XXV (Oxford: Clarendon Press, 1973), 97.

As a non-believer, that is the kind of Christian I can respect. He has the right priorities.