nagel on dawkins

February 12, 2007

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I found the following review of The God Delusion by Thomas Nagel very helpful in thinking critically about the book. Excerpts follow – italics mine.

“The Fear of Religion” by Thomas Nagel

Richard Dawkins, the most prominent and accomplished scientific writer of our time, is convinced that religion is the enemy of science. Not just fundamentalist or fanatical or extremist religion, but all religion that admits faith as a ground of belief and asserts the existence of God.

***

The important message is a theoretical one, about the reach of a certain kind of scientific explanation. At the core of the book, in a chapter titled “Why There Almost Certainly Is No God,” Dawkins sets out with care his position on a question of which the importance cannot be exaggerated: the question of what explains the existence and character of the astounding natural order we can observe in the universe we inhabit… In Dawkins's view, the ultimate explanation of everything, including evolution, may be found in the laws of physics, which explain the laws of chemistry, which explain the existence and the functioning of the self-replicating molecules that underlie the biological process of genetic mutation and natural selection.

***

[Why not dismiss the Argument from Design?] Scientific inference to the best explanation of what we can observe often leads to the discovery of things that are themselves unobservable by perception and detectable only by their effects. In this sense, God might be no more and no less observable than an electron or the Big Bang. [Furthermore,] science often concludes that what we observe is to be explained by causes that are not only unobservable, but totally different from anything that has ever been observed, and very difficult to grasp intuitively. To be sure, the hypothesis of a divine creator is not yet a scientific theory with testable consequences independent of the observations on which it is based. And the purposes of such a creator remain obscure, given what we know about the world. But… it is hardly surprising that God, the bodiless designer, while to some extent describable theoretically and detectable by his effects, is resistant to full intuitive understanding.

…If the God hypothesis makes sense at all, it offers a different kind of explanation from those of physical science: purpose or intention of a mind without a body, capable nevertheless of creating and forming the entire physical world. The point of the hypothesis is to claim that not all explanation is physical, and that there is a mental, purposive, or intentional explanation more fundamental than the basic laws of physics, because it explains even them.

All explanations come to an end somewhere. The real opposition between Dawkins's physicalist naturalism and the God hypothesis is a disagreement over whether this end point is physical, extensional, and purposeless, or mental, intentional, and purposive. On either view, the ultimate explanation is not itself explained. The God hypothesis does not explain the existence of God, and naturalistic physicalism does not explain the laws of physics.

This entire dialectic leaves out another possibility, namely that there are teleological principles in nature that are explained neither by intentional design nor by purposeless physical causation–principles that therefore provide an independent end point of explanation for the existence and form of living things. That, more or less, is the Aristotelian view that was displaced by the scientific revolution.

***

[Why dismiss the Argument from Design?] The physical improbability of such complexity's arising can be radically reduced if it is seen as the result of an enormous number of very small developmental steps, in each of which chance plays a part, together with a selective force that favors the survival of some of those forms over others. This is accomplished by the theory of heritable variation, due to repeated small mutations in the genetic material, together with natural selection, due to the differential adaptation of these biological variations to the environments in which they emerge. The result is the appearance of design without design, purely on the basis of a combination of physical causes operating over billions of years.

***

[Why not dismiss the Argument from Design?] The problem is this. The theory of evolution through heritable variation and natural selection reduces the improbability of organizational complexity by breaking the process down into a very long series of small steps, each of which is not all that improbable. But each of the steps involves a mutation in a carrier of genetic information–an enormously complex molecule capable both of self-replication and of generating out of surrounding matter a functioning organism that can house it. The molecule is moreover capable sometimes of surviving a slight mutation in its structure to generate a slightly different organism that can also survive. Without such a replicating system there could not be heritable variation, and without heritable variation there could not be natural selection favoring those organisms, and their underlying genes, that are best adapted to the environment.

The entire apparatus of evolutionary explanation therefore depends on the prior existence of genetic material with these remarkable properties. Since 1953 we have known what that material is, and scientists are continually learning more about how DNA does what it does. But since the existence of this material or something like it is a precondition of the possibility of evolution, evolutionary theory cannot explain its existence…

Dawkins recognizes the problem, but his response to it is pure hand-waving. First, he says it only had to happen once. Next, he says that there are, at a conservative estimate, a billion billion planets in the universe with life-friendly physical and chemical environments like ours. So all we have to suppose is that the probability of something like DNA forming under such conditions, given the laws of physics, is not much less than one in a billion billion. And he points out, invoking the so-called anthropic principle, that even if it happened on only one planet, it is no accident that we are able to observe it, since the appearance of life is a condition of our existence.

[but] no one has a theory that would support anything remotely near such a high probability as one in a billion billion. Naturally there is speculation about possible non-biological chemical precursors of DNA or RNA. But at this point the origin of life remains, in light of what is known about the huge size, the extreme specificity, and the exquisite functional precision of the genetic material, a mystery–an event that could not have occurred by chance and to which no significant probability can be assigned on the basis of what we know of the laws of physics and chemistry.

***

I agree with Dawkins that the issue of design versus purely physical causation is a scientific question… But although I am as much of an outsider to religion as he is, I believe it is much more difficult to settle the question than he thinks. I also suspect there are other possibilities besides these two that have not even been thought of yet. The fear of religion leads too many scientifically minded atheists to cling to a defensive, world-flattening reductionism. Dawkins, like many of his contemporaries, is hobbled by the assumption that the only alternative to religion is to insist that the ultimate explanation of everything must lie in particle physics, string theory, or whatever purely extensional laws govern the elements of which the material world is composed.

This reductionist dream is nourished by the extraordinary success of the physical sciences in our time, not least in their recent application to the understanding of life through molecular biology. It is natural to try to take any successful intellectual method as far as it will go. Yet the impulse to find an explanation of everything in physics has over the last fifty years gotten out of control. The concepts of physical science provide a very special, and partial, description of the world that experience reveals to us. It is the world with all subjective consciousness, sensory appearances, thought, value, purpose, and will left out. What remains is the mathematically describable order of things and events in space and time.

That conceptual purification launched the extraordinary development of physics and chemistry that has taken place since the seventeenth century. But reductive physicalism turns this description into an exclusive ontology. The reductionist project usually tries to reclaim some of the originally excluded aspects of the world, by analyzing them in physical–that is, behavioral or neurophysiological–terms; but it denies reality to what cannot be so reduced. I believe the project is doomed–that conscious experience, thought, value, and so forth are not illusions, even though they cannot be identified with physical facts.

I also think that there is no reason to undertake the project in the first place. We have more than one form of understanding. Different forms of understanding are needed for different kinds of subject matter. The great achievements of physical science do not make it capable of encompassing everything, from mathematics to ethics to the experiences of a living animal. We have no reason to dismiss moral reasoning, introspection, or conceptual analysis as ways of discovering the truth just because they are not physics.

Any anti-reductionist view leaves us with very serious problems about how the mutually irreducible types of truths about the world are related. At least part of the truth about us is that we are physical organisms composed of ordinary chemical elements. If thinking, feeling, and valuing aren't merely complicated physical states of the organism, what are they? What is their relation to the brain processes on which they seem to depend? More: if evolution is a purely physical causal process, how can it have brought into existence conscious beings?

A religious worldview is only one response to the conviction that the physical description of the world is incomplete. Dawkins says with some justice that the will of God provides a too easy explanation of anything we cannot otherwise understand, and therefore brings inquiry to a stop. Religion need not have this effect, but it can. It would be more reasonable, in my estimation, to admit that we do not now have the understanding or the knowledge on which to base a comprehensive theory of reality.

Dawkins seems to believe that if people could be persuaded to give up the God Hypothesis on scientific grounds, the world would be a better place–not just intellectually, but also morally and politically. He is horrified–as who cannot be?–by the dreadful things that continue to be done in the name of religion, and he argues that the sort of religious conviction that includes a built-in resistance to reason is the true motive behind many of them. But there is no connection between the fascinating philosophical and scientific questions posed by the argument from design and the attacks of September 11. Blind faith and the authority of dogma are dangerous; the view that we can make ultimate sense of the world only by understanding it as the expression of mind or purpose is not. It is unreasonable to think that one must refute the second in order to resist the first.

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