Daily Archives: July 20, 2012

The Design Argument

The fifth of Kreeft & Tacelli’s 20 arguments for the existence of God is the Design Argument. This is perhaps the most important argument in the whole collection. It’s the one that seems the most obviously valid to most theists and the most obviously invalid to most atheists, who consider it to have been definitively debunked by Darwin.

*

Summary of the argument

  1. The universe shows a remarkable amount of intelligible order.
  2. Either this order came about by chance, or it was designed by something intelligent.
  3. Chance is not a credible explanation because “we can understand chance only against a background of order.” Darwin’s theory of the nonrandom survival of random variation also assumes the prior existence of intelligible order (“The survival of the fittest presupposes the arrival of the fit”) and can therefore not explain it.
  4. Therefore, the universe was designed by something intelligent.
  5. In order to have designed the entire universe, the designers must exist outside the universe and be non-physical in nature. It is therefore natural to identify them — or, rather, “him” — with God.

The intelligent design (ID) hypothesis is usually presented as a stripped-down version of creationism, an alternative to Darwin’s theory of the origin of species. However, while K & T appear to be evolution skeptics themselves (they cite Michael Denton and Phillip E. Johnson with approval), they maintain that the Design Argument would still be just as valid and convincing if the Darwinian hypothesis were true. In my critical comments below, I will therefore assume biological orthodoxy: that all organisms arose from a common ancestor via descent with modification driven primarily by natural selection.

*

Chance and design do not exhaust the possibilities.

Why does my reflection look like my face? Should we ascribe the correspondence to chance or design? (Note that I am not asking about the origin of the reflective surface, which could just as well be a naturally occurring puddle as an intelligently designed mirror, but about the reflection itself.) We unhesitatingly ascribe the resemblance between Arrangement in Grey and Black No. 1 and Anna Whistler to design, and my reflection resembles my face far more exactly than any portrait resembles its subject — so should we infer that there is some unseen intelligent agent busily designing all the reflections we see? After all, the only other option — that the incredibly detailed, point-by-point correspondence between my face and my reflection is just a coincidence — is even more absurd.

Clearly this is a false dichotomy, and the true explanation for the correspondence is what we might call blind regularity. (Another term which suggests itself, necessity, carries too much philosophical baggage to be suitable here.)

A detailed discussion of chance, regularity, and design is beyond the scope of this post (as I realized after typing out a very long tangent on the subject, which I decided not to include). The point I want to make is just that “chance,” as it is used in this argument, doesn’t really mean chance; it covers anything that isn’t intelligent design, including mindless adherence to the laws of physics. The dichotomy K & T are advocating would force us to say either that the sun always rises in the east and never in the west just “by chance” — an absurdly improbable coincidence — or else that it is guided in its path by an intelligent agent — Phoebus in his chariot, essentially. The parody theory of “Intelligent Falling” comes to mind.

So, wherever K & T write “chance,” read “unintelligent forces” — not necessarily chance as that word is ordinarily understood.

*

What Darwinism presupposes — and what it doesn’t

“The survival of the fittest presupposes the arrival of the fit” sounds right at first but is actually a misrepresentation of Darwin’s theory. K & T write:

If the Darwinian theory has shown anything, it has shown, in a general way, how species may have descended from others through random mutation; and how survival of these species can be accounted for by natural selection—by the fitness of some species to survive in their environment.

This makes it sound as if natural selection plays no role in the actual origin of new species but serves only to explain why some species, after having come into existence by pure chance, continue to survive. This is obviously not what Darwin had in mind when he wrote On the Origin of Species by Means of Natural Selection. Although it is true that natural selection is a wholly negative process, weeding out some of what comes into being by random mutation, it nevertheless plays a creative role. Without natural selection, new “fit” species would never come into existence in the first place because every random change for the better would be canceled out by thousands of random changes for the worse. Natural selection functions as a ratchet, preserving only the good changes and allowing them to accumulate in a way which would never otherwise be possible. Or, to vary the metaphor, random mutation would never serve up anything other than a structureless hunk of marble were it not for natural selection chipping away everything that doesn’t look like David.

So Darwinism does not presuppose the arrival of the fit; it is a true theory of the origin — not just the survival — of species. It explains a great deal of the apparent design in nature. However, it does presuppose the existence of DNA or something like it — bodies capable of creating copies of themselves with not-quite-perfect fidelity. That alone implies a pretty impressive level of intelligible order, perhaps enough to motivate the ID hypothesis even without the help of eyes and hearts and brains and all the other things for which natural selection is an adequate explanation.

*

Everything, including design, presupposes order.

Obviously the Darwinian theory itself cannot explain the origin of all the intelligible order in the universe, since it presupposes the existence of self-replicating structures.

Even more obviously, intelligent design cannot explain the origin of all the intelligible order in the universe, since it presupposes the existence of intelligent designers.

However, evolution and design do show us broadly what kinds of explanations of intelligible order are possible.

Watches, and the watchmakers who make them, show us that it is possible in principle for intelligible order to be the creation of an intelligent designer. Of course it’s not possible that life and the universe were designed by, say, George-Emile Eberhard — but perhaps by something like Eberhard, by some as-yet unknown intelligent agent.

Likewise, living organisms, and the Darwinian mechanism that makes them, show us that it is possible in principle for intelligible order to arise from a combination of random chance and blind regularity. Of course it’s not possible that life and the universe were created by natural selection as we know it — but perhaps by something like that, by some as-yet unknown unintelligent process.

*

Unfortunately, neither evolution nor design can offer a real answer to the ultimate question of why there is order rather than no-order. This is probably just as unanswerable as Leibniz’s “Why is there something rather than nothing?” Any conceivable answer to Leibniz’s question would itself be a “something” in need of explanation — and in the same way, any conceivable explanation of the origin or order would imply a mechanism of cause-and-effect, and thus some underlying order.

*

Design is an empirical question, not a philosophical deduction.

None of this means that there is anything illegitimate about the design hypothesis. Obviously, intelligent design is the correct explanation for the existence of a great many things — watches and computers and motorcycles and so on — and there’s no a priori reason why it couldn’t be the correct explanation for the existence of life or even of the entire known universe. Evolutionists who dismiss ID as unacceptable even in principle because it presupposes a creator and thus explains “exactly nothing” (Dawkins) are going much too far. Evolution may be more elegant and philosophically satisfying than ID because it explains more complex things in terms of simpler ones rather than vice versa, but none of that changes the fact that ID undeniably is the correct explanation for many things, and therefore cannot legitimately be ruled “meaningless” or “unscientific” or otherwise intellectually non-kosher.

However, creationists who assume that ID is the only possible explanation for complexity or intelligible order are also going too far. Design is a legitimate hypothesis — but that’s all it is. Like any other hypothesis, it must stand or fall on empirical grounds. “Order, therefore design” is not good enough because (1) design cannot logically be the source of all order, since it presupposes order; and (2) we have in Darwinian evolution an actual example of order arising without design, showing that this is possible in practice as well as in theory.

Proponents of ID often try to use Sherlock Holmes’ maxim from “The Adventure of the Blanched Soldier” — that once you have eliminated the impossible, whatever remains, however improbable, must be the truth — in an invalid manner. The argument goes something like this:

  1. X must have come into being either through intelligent design or through unintelligent processes (“chance”).
  2. No known unintelligent process can adequately explain X.
  3. Therefore, even in the absence of any positive evidence of design, we can conclude that X was designed.

This is invalid because there are actually four possibilities. X could be the work of (1) a known intelligent agent, such as Eberhard or some other human being; (2) an unknown intelligent agent, such as the “designer(s)” postulated by ID proponents; (3) a known unintelligent process, such as Darwinian evolution; or (4) an unknown unintelligent process. Of course no one takes the first possibility seriously where life or the universe is concerned; however, it’s hard to see why the fourth should be excluded from consideration. A more logically valid form of the above argument would be

  1. X must have come into being either through intelligent design or through unintelligent processes.
  2. No known agent or process — intelligent or unintelligent — can adequately explain X.
  3. Therefore, the cause of X is unknown and could be either intelligent or unintelligent in nature.

2 Comments

Filed under Evolution, God, Philosophy