Where the Conflict Really Lies: Science, Religion, and Naturalism (33 page)

They have
not
shown this. The typical procedure, one adopted by Darwin himself, is to point to the various sorts of eyes displayed by living things, lining them up in a series of apparently increasing adaptive complexity, with the mammalian eye at the top of the series. But that of course doesn’t actually show that it is biologically possible—that is, not prohibitively improbable—that later members of the series developed by Darwinian means from earlier members. To put it in terms of the scheme developed on p. 225, it has not been shown that there is a path through “design space” where (1) the first point is occupied by a design with no more than a light sensitive spot, as with certain relatively primitive animals, (2) each point (except the first) represents a design arising by way of heritable genetic variation (the main candidate is random genetic mutation) from the previous point, (3) each point is an adaptive step forward with respect to the previous point, or else a consequence, by way of spandrel or pleiotropy, of a design that is such a step forward, (4) each point is not prohibitively improbable with respect to the previous point, and (5) the last point is occupied by (correlated with) the design of the human eye. Of course this hasn’t been demonstrated at all. (What perhaps has been, if not demonstrated, at least shown to be reasonably plausible, is that
for all we know
there is such a series: no one has succeeded in showing that there
isn’t
any such series.
⁴⁷
) Not only don’t we know that there is such a path, we don’t even know how to go about determining whether or not there are such paths through design space. It’s simply not known how to make the relevant calculations; judgments
as to whether there are or aren’t any such pathways are very much seat of the pants, tenuous, hard to support, and, apparently, responsive to and coordinated with one’s metaphysical or theological views.

So
does
current evolutionary science give us a defeater for Paley design beliefs with respect to the eye? The sensible thing to think, here, is that we have a
partial
undercutting defeater for those beliefs (formed in that way).
⁴⁸
As we saw earlier, undercutting defeaters come in degrees. Evolutionary biologists present considerations designed to show how it could be that these structures have arisen by way of unguided Darwinian processes; they give us some reason to believe that this is possible. These considerations, when you first become aware of them, should
somewhat reduce
your confidence that these structures have been designed. How much should your confidence be reduced? That will depend upon several factors, including in particular what the rest of your belief structure is like—what else you believe, and how firmly you believe it. There is no general answer to the question “How much?”

We can see that the same ideas apply with respect to the fine-tuning consideration of
chapter 7
. Suppose we take those appeals to fine-tuning as the basis for arguments for design. Then various proposed objections—the anthropic objection, the normalizability objection, the many-worlds objection, the problem with ascertaining the relevant probabilities—seem to be reasonably plausible, even if not ultimately decisive.
⁴⁹
But if we take them as design discourse rather than argument, then none of these objections (with the possible exception of the third) is even relevant.

Now return to Behe. I concluded above that Behe’s arguments in
Darwin’s Black Box
and
The Edge of Evolution
, taken as discursive
arguments
, are by no means airtight. But suppose we take what Behe says, not as an argument, not as a discursive structure with premises and conclusion, but as a design discourse in the way we were thinking of Paley’s argument. Sometimes Behe himself seems to think this way: “There is an elephant in the roomful of scientists who are trying to explain the development of life. The elephant is labeled ‘intelligent design.’”
⁵⁰
This sounds as if Behe thinks that upon becoming acquainted with the structures he mentions, one is subject to a powerful inclination to believe that they are designed. These complex structures—the cilia, flagella, structures involved in blood clotting, and so on of
Darwin’s Black Box
and the molecular machines of
The Edge of Evolution
—these complex and beautifully tailored structures certainly
appear
to be designed. There is that great complexity joined to simplicity; there is that precise tailoring of the various parts to each other, a tailoring necessary to their performing their function at all; these things give all the appearances of devices that have been designed to produce a certain result. Indeed, we ordinarily think of them in that fashion; we speak of them as
functioning properly
or
working properly
, or
healthy
; we also speak of them as
defective
, as
unhealthy
, as
needing repair
, all of which fits in naturally with the supposition that they have been designed. These structures look as if they have been designed, and it takes considerable training and effort to resist that belief. Thus Sir Francis Crick, himself very far from a friend of divine design: “Biologists must constantly keep in mind that what they see was not designed, but rather evolved.”
⁵¹
Clearly the reason they must constantly keep this in mind is that the structures they deal with look for all the world as if they
were
designed.

Has contemporary Darwinian biology provided undercutting defeaters for Behe design beliefs, beliefs that those cellular structures have been designed? Here the answer is clearly “no.” The structures Behe mentions (together with many more structures at the molecular level) are such that, as Behe says, no Darwinian explanations have so far been forthcoming. And it isn’t only Behe who reports this. James Shapiro, a molecular biologist, and no friend or supporter of the idea that structures of these sorts have been designed: “there are no detailed Darwinian accounts for the evolution of any fundamental biochemical or cellular system, only a variety of wishful speculations.”
⁵²
For these structures at the cellular and molecular level, there aren’t (yet) any Darwinian accounts or explanations. Those ardent devotees of natural selection who proclaim that contemporary Darwinian science has completely explained the apparent design in the biological realm, and in fact thus completely explained it away, are mistaken about the entire molecular level. Here (so it seems) there isn’t a lot beyond just-so stories.
⁵³

If this is true, then there aren’t any defeaters, either rebutting or undercutting, for Behe design beliefs. So the real significance of Behe’s work, as I see it, is not that he has produced incontrovertible arguments for the conclusion that these systems have been designed; it is rather that he has produced several design discourses, several sets of circumstances in which design perception occurs, for which in fact there aren’t any defeaters. The difference, of course, is this: pointing to deficiencies and holes in Behe taken as producing an argument, as Draper (for example) skillfully does, fails to show that there are defeaters for Behe design beliefs.

But then what overall conclusion should we draw about these design discourses? I said we have partial defeaters for the design
discourses at the level of gross anatomy; we have partial defeaters for design beliefs having to do with the eye, with the structure of limbs, and the like. We don’t have any such defeaters for Behe design beliefs at the molecular and cellular level. How should we put this together? Should we go with those who assimilate the latter to the former, arguing that if we just wait awhile (after all, molecular biology and biochemistry have been with us only since the 1950s or so), there will be plausible Darwinian explanations for them, just as there are (as they think) for structures at the gross anatomical level? Or should we go with partisans of design, who point out that it isn’t at all clear that there are defeaters at the gross anatomical level, and it
is
clear that there aren’t any at the cellular level, so that on balance the design conclusion is the stronger?

Here, I think, the friends of design have the better of the argument; the partisans of Darwinism are tugging the laboring oar. True, there are reasonably plausible Darwinian explanations at the anatomical level for many structures and systems; that fact should perhaps reduce the confidence with which one forms design beliefs at the cellular level. So we can say that here too we have a partial defeater. But (in my judgment) it is an
extremely
partial defeater. So the right conclusion, as it seems to me, is that Behe’s design discourses are in fact rather successful: his account of the structures he describes certainly do produce the impression of design. Biological science, so far, anyway, has at best produced weak defeaters for these design beliefs.
⁵⁴

This question whether design beliefs are defeated by Darwinian suggestions is actually much more complex, involving a good deal of the epistemology of defeat and deflection. Here I will just point to
some of that complexity. First, assume that in fact there is an impulse, an inclination to believe that these biological phenomena are designed, as is attested even by such opponents of divine design as Sir Francis Crick. Second, as I noted above, a belief—for definiteness, consider a basic belief—can be defeated. But such beliefs can also be deflected; we must distinguish between defeat and deflection. A
defeater
D for a belief B is another belief I acquire, such that as long as I hold that belief D, I cannot rationally (given my noetic structure) continue to believe B (and a partial defeater requires that I hold B less firmly). A belief
deflector
D* for a (potential) belief B, is, roughly speaking, a belief I already hold such that as long as I hold it (and given my noetic structure) I can’t rationally come to hold B. So, with respect to the earlier example of a defeater (p. 248), I said you got a defeater for your belief that you see a sheep in the field if I, whom you know to be the owner of the field, come along and tell you that although there are no sheep in the field, there is a canine sheep look-alike that often frequents the field. But you won’t get a defeater, here, if you already think that I am unreliable on this topic, or that I have a lot to gain by getting you to doubt that there is a sheep there, or if you believe that there aren’t any dogs in this part of the world, or that no dogs ever look like sheep from the distance in question, and so on. In these cases the looming defeater (defeater belief) will be deflected.

The above characterization of a deflector is too broad, in that it assigns deflectorhood to almost any belief with respect to a belief that is sufficiently irrational. Thus consider the belief B that there has not been a past; this belief, I take it, is irrational, in the sense that a properly functioning human being with anything like a standard noetic structure will not form B. But then nearly any other belief I hold is (on the above account) a deflector with respect to B: any other belief is such that as long as I hold it, I can’t rationally acquire B. What has to be added is a clause roughly to the effect that a deflector belief D
for a belief B must be such that in the relevant circumstances, if D were not present in my noetic structure, I would have formed B. True, this account involves a counterfactual, inviting the sort of grief to which analyses involving counterfactuals often succumb; but perhaps it is close enough for present purposes. In any event, I leave as homework the project of refining the account.

The question is whether Darwinian considerations present a defeater for the design beliefs a person S forms in response to a given design discourse. To make the discussion manageable, assume that the occasion in question is the first on which S is confronted with the design discourse in question; suppose she is then confronted for the first time by relevant Darwinian considerations. Whether these Darwinian considerations defeat S’s design beliefs will depend upon the rest of what S believes. If S is already a theist, S believes that these things (and indeed the whole universe) is designed. Under those conditions, Darwinian considerations will not give S a defeater for the design belief in question; her theistic belief is a defeater-deflector for the looming defeater. Here too, however, there are further complexities: what happens depends on the strength of S’s theistic belief, and also on the strength of her reaction to the potential Darwinian defeating belief. If the Darwinian considerations produce a strong enough impulse to form the belief that the phenomena in question are
not
designed, if
that
impulse overwhelms her initial theistic belief, then defeat of the design belief will not be deflected, and indeed S will wind up with a defeater for her initial theistic belief.

What about the serious naturalist? She comes in varieties. One such variety is a naturalist who is wholly convinced that the biological world we find around us came to be just by the grace of unguided evolution. Such a naturalist will have a deflector for the relevant design beliefs, and will presumably not form such beliefs (she may follow Crick’s advice, repeatedly telling herself that it evolved and isn’t designed)—unless, of course, the impulse to form those design
beliefs is overwhelming; in that case the impulse to form the design belief will outweigh the potential belief-deflector. Another kind of naturalist might believe that the biological world and its denizens have not been designed by God, but she may leave slightly ajar the door to belief that they have been designed by some other beings. If so, she might still form a design belief in the circumstances, perhaps thinking these biological phenomena have been designed by ancient astronauts, creatures from a scientifically advanced culture on another planet who intervened in the evolution of life on our planet a half billion years ago. (By now these creatures would be pretty long in the tooth.) For most of us, this scenario, though perhaps possible, is pretty unlikely; for S to come to this conclusion, both the design impulse and belief that God has not designed these phenomena would have to be strong indeed.