Where the Conflict Really Lies: Science, Religion, and Naturalism (4 page)

For simplicity (and because we are thinking about Dawkins, an enthusiast for natural selection), let’s stick with what above I called “Darwinism,” the idea that the main or possibly even only mechanism driving the whole process of evolution is natural selection culling random genetic mutation. A Darwinist will think there is a
complete Darwinian history
for every contemporary species, and indeed for every contemporary organism.
²⁰
Start with the population of prokaryotes (e.g., bacteria and blue-green algae) to be found on earth some 3 billion years ago. There is in principle a complete history specifying which genetic mutations occurred with respect to each member of that population, which of these mutations were heritable and adaptive, and which then successfully spread through the population. This history would go on to specify (vagueness aside) when, as a result of this process, the first single-celled eukaryotes (creatures with a proper nucleus) appeared; it would then describe how, in this way, the first new species came to be, the first new genera, the first new phyla, and so on. It would proceed through the Cambrian explosion, specifying in complete
detail which adaptive and heritable mutations arose at what times and in which creatures, and how they then spread through the population, eventually issuing in that remarkable eruption of life forms. Continuing over the eons, this history would trace in detail the development of all forms of life: the invertebrates, the various forms of vertebrate life including fish, reptiles, birds, and mammals; it would end with a description of all the contemporary forms of life.

This history, if written, would occupy an enormous library: call it the Library of Life. The claim is not, of course, that we are or ever will be in possession of that library. We don’t have anything like detailed knowledge of any of the books it contains, or even of any chapters or passages in any of those books. The Darwinian claim is only that (1) there is such a history, (2) there is
good evidence
for current views as to the overall shape of the history, and (3) we have some informed guesses as to how, at a high level of abstraction, some of the transitions occurred: examples would be the sorts of guesses made by Dawkins as to the origin and development of the mammalian eye, or the common suggestion that the bones in the mammalian middle ear developed from the reptilian jawbone.

Now there is nothing here, so far, to suggest that this whole process was unguided; it could have been superintended and orchestrated by God. For all the library says, God could have achieved the results he wanted by causing the right mutations to arise at the right times, letting natural selection do the rest. Another possibility: Thomas Huxley, Darwin’s bulldog, was an agnostic (and in fact invented the term); nevertheless he suggested that God could have set things up initially so that the right mutations would be forthcoming at the right times, leading to the results he wanted.
²¹
No
doubt there are other ways in which he could have directed and orchestrated the process. Dawkins’s claim, of course, is that there is no such intelligent agent guiding the process;
“the evidence of evolution
,” he says,
“reveals a universe without design
.” What makes him think this is true? How does he propose to argue for this claim?

Not, naturally enough, by specifying chapter and verse in relevant volumes of the library and showing or even arguing that the processes involved in those transitions were not in fact overseen or guided by such an agent; our powers are a bit slim for that. Instead, he tries to show that it is
possible
that unguided natural selection should have produced all these wonders; it
could be
that they have all come to be just by virtue of unguided natural selection. He does this, first, by attacking arguments for the conclusion that natural selection could
not
have done so. Or rather, he attacks certain kinds of such arguments, ignoring others. Among those he ignores, for example, is John Locke’s claim that “it is as impossible to conceive that ever pure incogitative Matter should produce a thinking intelligent Being, as that nothing should of itself produce Matter.”
²²
Many have concurred with Locke, but Dawkins fails to so much as mention this kind of claim. Nor does he try to show either that there is no such person as God, or that, if there is, it is not possible that he should have somehow set up and directed the whole process.
²³
And why should he? After all, he’s a biologist and not a philosopher.

Instead, Dawkins tries to refute some of the more specific and specifically biological arguments to the effect that unguided natural
selection could not have produced certain of the wonders of the living world—the mammalian eye, for example, or the wing, or the bat’s sonar. He argues that the objectors have not made their case. Here he sometimes stumbles; for example, he apparently confuses the question “What good is 5 percent of an eye?” with “What good is 5 percent vision?”: “An ancient animal with 5 per cent of an eye,” he says, “might indeed have used it for something other than sight, but it seems to me at least as likely that it used it for 5 per cent vision.”
²⁴
But not just any old 5 percent of an eye will produce 5 percent vision; indeed there may not be
any
5 percent of an eye that produces 5 percent vision.

Just for purposes of argument, let’s concede that Dawkins succeeds in refuting each of these claims of impossibility. Clearly that doesn’t entail that the impossibility claims are false; it shows only that certain arguments for them are not cogent. The question still remains:
is
it possible that unguided natural selection generate all the stunning marvels of the living world? Dawkins puts this question in the following tripartite fashion:

(3) Is there a continuous series of Xs connecting the modern human eye to a state with no eye at all?
(4) Considering each member of the series of hypothetical Xs connecting the human eye to no eye at all, is it plausible that every one of them was made available by random mutation of its predecessor?
(5) Considering each member of the series of Xs connecting the human eye to no eye at all, is it plausible that every one of them worked sufficiently well that it assisted the survival and reproduction of the animals concerned?
²⁵

Compressing things a bit, we could put the question as follows. Imagine a three-dimensional space—“organic space,” as we might call it—where each of the countably infinite points is a possible life form. Then the Big Question is:

(BQ) Is there a path through organic space connecting, say, some ancient population of unicellular life with the human eye, where each point on the path could plausibly have come from a preceding point by way of a heritable random genetic mutation that was adaptively useful, and that could plausibly then have spread through the appropriate population by way of unguided natural selection?
²⁶

A couple of comments on (BQ). First, the human eye is just a stand-in for life forms generally; the question is not merely whether the human eye could have developed in this way, but whether
all
the current life forms could have. Second, we must start with an
actual
(not merely possible) population of unicellular life, a population that did in fact exist: the claim is that human beings (and hence the human eye) could have developed via unguided natural selection from some population of unicellular organisms that actually existed. Third, the other life forms on the path—the ones “between” the population of unicellular organisms and human beings—must be possible, but need not be actually existent. (That is, they need not be actually instantiated or exemplified; it’s enough if they are possibly instantiated.) Dawkins is really asking whether it is
plausible
that the human eye develop in this way, starting from some population of unicellular organisms. Of course if in fact the eye
did
develop in this way, there would have to be such a path connecting life forms that had existent
instantiations. Fourth, the points on the path will have to be temporally indexed, with the temporal distance between a pair of points on the path being sufficient for the relevant mutation to spread through the population in question. That means that the time elapsed from that initial population of unicellular organisms to the appearance of the eye imposes a constraint on the number of points the path in question can contain and the temporal distance between them; the number of points the path contains and the temporal distance between them can be large but is not unlimited.

Finally, and crucially, what is the force of “could plausibly” in “each point along the path is such that it
could plausibly
have come from a preceding point on the path by way of a heritable random genetic mutation?” We’re not talking broadly logical possibility, of course; we’re not asking whether there is a possible world in which this development takes place. That would be much too weak; to use a Dawkinsian example, there are possible worlds in which the bronze statues in the park (constituted just as they presently are) wave goodbye when you leave. We are instead talking about something like
biological
possibility, and, as Dawkins thinks of biological possibility, it is to be explained in terms of
probability
. A given point on a path could plausibly have come from a preceding point by way of genetic mutation just if it is not too improbable that it do so. It might be possible in the broadly logical sense that a sufficiently complex single mutation take us all the way from a paradigm reptile to a paradigm mammal—possible, but far too unlikely. So the mutations must be reasonably probable, not too improbable, with respect to the previous point. Not too improbable, of course, apart from any special divine aid or special divine action. The mutation in question would have to occur and be caused in the usual way—by way of cosmic radiation, or x-ray, or chemical agent or whatever—but not by way of special divine action. How much improbability is too much? Here one can answer only in the vaguest terms. Dawkins suggests, sensibly enough, that
the improbability would have to be much less than that of that statue waving at us as we leave the park.

How does Dawkins answer (BQ), or rather, his tripartite version of it? (3), you recall, was the question “Is there a continuous series of Xs connecting the modern human eye to a state with no eye at all?” His reply: “It seems to me clear that the answer has to be yes, provided only that we allow ourselves a
sufficiently large
series of Xs.”
²⁷
No doubt he’s right about (3); surely there is such a relevant series. We can see this as follows: consider a particular human eye—one of Dawkins’s, for example; assign a number to each cell contained in that eye (as with certain kinds of build-it-yourself toy kits); let the first member of the series be a creature that has cell number 1, the second be one that contains cells number 2 and number 1; the third contain cell number 3 plus cells number 1 and 2, and so on. This won’t quite work; for this eye to function, there will also have to be an appropriate brain or part of a brain to which it is connected by an optic nerve. But you get the idea: clearly there is such a series. Of course that by itself doesn’t show much; if it’s to be relevant, the length of the series will have to be constrained by the time available, and each step in the series will have to be such that it can arise by way of genetic mutation from a previous step. Furthermore (and crucially), each mutation will have to be fitness-conferring (or at least not unduly costly in terms of fitness), so that it’s not too improbable that they be preserved by natural selection. This is where his answers to (4) and (5) come in.

Dawkins’s answer to (4), (Considering each member of the series of hypothetical Xs connecting the human eye to no eye at all, is it plausible that every one of them was made available by random mutation of its predecessor?): “My feeling is that, provided the difference between neighboring intermediates in our series leading to the eye is
sufficiently
small
, the necessary mutations are almost bound to be forthcoming.” Finally question (5): Considering each member of the series of Xs connecting the human eye to no eye at all, is it plausible that every one of them worked sufficiently well that it assisted the survival and reproduction of the animals concerned? As Dawkins notes, some people claim that the obvious answer is “no”; he argues that they are mistaken. These people point to a particular structure or organ and claim that there isn’t a Darwinian series for that structure or organ; Dawkins makes suggestions as to how such a series might in fact go.

There are two basic ways in which Dawkins’s argument is weak. First, returning to BQ, there is surely no
guarantee
that there is a not-too-improbable path through organic space from some early population of unicellular organisms to human beings, or, for that matter, to fruit flies. It might be, as Michael Behe claims, that some structures simply can’t be reached by way of small steps (each advantageous or not too disadvantageous) from preceding life forms.
²⁸
Among his proposed examples: the bacterial cilium, the cascade of electrical activity that occurs when a light sensitive spot is hit by a photon, blood clotting, the mammalian immune system, and the complicated molecular machines to be found in any living cell. Many have rejected Behe’s specific arguments here; still, perhaps he’s right. (I consider some of Behe’s arguments in
chapter 7
.) Perhaps no matter how small you make the steps, there are life forms that can’t be reached from previous forms, except at the cost of astronomical, prohibitive improbability. How could we tell that this isn’t so? True, Dawkins says that his feeling is that indeed it isn’t so; but how much confidence can we put in feelings and guesses?

So the first weakness in Dawkins’s argument is that the premises, his answers to questions (4) and (5) above, are controversial,
unsupported, and pretty much guesswork. There is no attempt at the sort of serious calculation that would surely be required for a genuine answer. No doubt such a calculation and hence an answer to those questions is at present far beyond our knowledge and powers; no doubt it would be unreasonable to require such a calculation; still, the fact remains we don’t have a serious answer.