When I learned of Thomas Nagel’s latest book Mind and Cosmos: Why the Materialist Neo-Darwinian Conception of Nature is Almost Certainly False, I looked a little further into what this atheist philosopher has to say. This has led me to make a brief digression from my series of comments on Richard Dawkins' Greatest Show on Earth, as I think it’s worth highlighting some of Nagel's comments.
Following the Dover trial in the USA, he wrote a paper 'Public Education and Intelligent Design' which was published in Philosophy & Public Affairs, 36(2), p187-205, in which he discusses the issues in the context of the Establishment Clause of the US Constitution. In the course of doing this he makes many perceptive observations regarding the debate about evolution and intelligent design (ID). When I read the paper I highlighted a lot of it, but clearly must be very selective about what I quote here. I encourage readers who are interested in these issues to read the whole of Nagel's paper.
The main points he makes are:
- ID is distinct from creationism, because it is based on scientific observations and inference rather than a religious authority, and it is open to scientific scrutiny.
- Because the basis for ID is scientific, it cannot simply be dismissed from consideration as non-science - to do so is just a feeble excuse or ruse to try to avoid facing up to the legitimate questions it raises.
- Neither can the possibility of a supernatural designer - a god - be summarily dismissed; it is a legitimate a priori worldview. Not only that, but the actions of such a being may be scientifically detectable.
- Claims about the certain truth of evolution are exaggerated, not supported by the evidence.
- The theory of evolution is not immune to scientific challenges - though many of its proponents speak as if it were - and such challenges should be taken seriously.
- The exaggerated claims for evolution and illegitimate refusal to take seriously any challenges to it, is leading to evolution being taught in a less than academically responsible way.
I'll now amplify and illustrate these points.
1. ID is distinct from creationism, because it is based on scientific observations and inference rather than a religious authority.
ID is very different from creation science. To an outsider, at least, it does not seem to depend on massive distortion of the evidence and hopeless incoherencies in its interpretation. Nor does it depend, like biblical literalism, on the assumption that the truth of ID is immune to empirical evidence to the contrary. What it does depend on is the assumption that the hypothesis of a designer makes sense and cannot be ruled out as impossible or assigned a vanishingly small probability in advance. Once it is assigned a significant prior probability, it becomes a serious candidate for support by empirical evidence, in particular empirical evidence against the sufficiency of standard evolutionary theory to account for the observational data. Critics take issue with the claims made by defenders of ID about what standard evolutionary mechanisms can accomplish, and argue that they depend on faulty assumptions. Whatever the merits, however, that is clearly a scientific disagreement, not a disagreement between science and something else. (pp196-7)
ID is a different story. Its defense requires only that design be admitted as a possibility, not that it be regarded as empirically unassailable. It would be difficult to argue that the admission of that possibility is inconsistent with the standards of scientific rationality. (p199)
Those who offer empirical evidence for ID do not have to argue that a completely nonpurposive explanation is impossible, only that it is very unlikely, given the evidence available. That is a scientific claim, though a contestable one. (p199-200)
2. Because the case for ID is essentially a scientific enterprise, it cannot simply be dismissed from consideration as non-science - to try do so is just a feeble excuse or ruse to try to avoid facing up to the legitimate questions it raises.
No one suggests that the theory [of evolution] is not science, even though the historical process it describes cannot be directly observed, but must be inferred from currently available data. It is therefore puzzling that the denial of this inference, i.e., the claim that the evidence offered for the theory does not support the kind of explanation it proposes, and that the purposive alternative has not been displaced, should be dismissed as not science. The contention seems to be that, although science can demonstrate the falsehood of the design hypothesis, no evidence against that demonstration can be regarded as scientific support for the hypothesis. (p188-9)
The conceivability of the design alternative is part of the background for understanding evolutionary theory. To make the assumption of its falsehood a condition of scientific rationality seems almost incoherent. (p201)
3. The possibility of a supernatural designer - a god - cannot be summarily dismissed - it is a legitimate a priori worldview. Not only that, but the actions of such a being may be scientifically detectable.
Immediately following the preceding quote from p189 he says:
[The contention seems to be ...] Something about the nature of the conclusion, that it involves the purposes of a supernatural being, rules it out as science. (p189)
And this is the crux of the anti-ID argument. It’s not that the arguments themselves are unsound, only that the conclusion is unacceptable - even if true!
The denier that ID is science faces the following dilemma. Either he admits that the intervention of such a designer is possible, or he does not. If he does not, he must explain why that belief is more scientific than the belief that a designer is possible. If on the other hand he believes that a designer is possible, then he can argue that the evidence is overwhelmingly against the actions of such a designer, but he cannot say that someone who offers evidence on the other side is doing something of a fundamentally different kind. All he can say about that person is that he is scientifically mistaken. (p195)
Especially interesting are his comments that the actions of a god could be scientifically detectable:
So the purposes and intentions of God, if there is a god, and the nature of his will, are not possible subjects of a scientific theory or scientific explanation. But that does not imply that there cannot be scientific evidence for or against the intervention of such a non-law-governed cause in the natural order. (p189)
I suspect that the assumption that science can never provide evidence for the occurrence of something that cannot be scientifically explained is the principal reason for the belief that ID cannot be science; but so far as I can see, that assumption is without merit. (p190)
4. Claims about the certain truth of evolution are exaggerated, not supported by the evidence.
Referring to the theory of evolution he observes:
To rule it out decisively would require that the sufficiency of standard evolutionary mechanisms to account for the entire evolution of life should have been clearly established by presently available evidence. So far as I can tell, in spite of the rhetoric to the contrary, nothing close to this has been done. (p199)
A great deal depends on the likelihood that the complex chemical systems we observe arose through a sufficiently long sequence of random mutations in DNA, each of which enhanced fitness. It is difficult to find in the accessible literature the grounds for evolutionary biologists’ confidence about this. (p199)
5. The theory of evolution is not immune to scientific challenges, and such challenges should be taken seriously.
To begin with he reminds us that any scientific theory must at least in principle be falsifiable:
I assume it will be granted by everyone that, even though the past cannot be directly observed, a scientific argument against the Darwinian theory of evolution is not impossible. If it were impossible, that would cast doubt on whether the theory is itself science.
And he recognises that the progress made in biochemistry and genetics opens up the possibility of such scrutiny.
For example, as we learn more about the behavior of the genetic material, and more about how the properties of organisms depend on it, it will be possible to give more precise answers to questions about the rate at which viable mutations can occur randomly as a result of physical accident, the kinds of phenotypic changes they can generate, and the number of generations within which specific changes would have had to occur to make the theory fit the development of organisms as we know them. Together with calculations of the numbers of individual organisms that have been involved in the major transitions in evolution, this should make it possible to evaluate the theory mathematically. (p190)
This of course is a key aspect of the ID challenge to the theory of evolution. And Nagel thinks that Michael Behe makes a valid point when he says:
alterations to DNA over the course of the history of life on earth must have included many changes that we have no statistical right to expect, ones that were beneficial beyond the wildest reach of probability. [from Edge of Evolution]
Like Kauffman, he believes that random mutation is not sufficient to explain the range of variation on which natural selection must have acted to yield the history of life: some of the variation was not due to chance. This seems on the face of it to be a scientific claim, about what the evidence suggests, and one that is not self-evidently absurd. (p192)
But he notes that ID arguments are sidestepped rather than refuted or even considered at all:
That [‘ID is hopelessly bad science’] would be true if ID, like young earth creationism, can be refuted by the empirical evidence even if one starts by assuming that the possibility of a god who could intervene cannot be ruled out in advance. So far as I can tell, however, no such refutation has even been offered, let alone established. What have been offered instead are necessarily speculative proposals about how the problems posed by Behe might be handled by evolutionary theory, declarations that no hypothesis involving divine intervention counts as science, and assurances that evolutionary theory is not inconsistent with the existence of God. (p202)
6. The exaggerated claims for evolution and illegitimate refusal to take seriously any challenges to it, is leading to evolution being taught in a less than academic way.
The political urge to defend science education against the threats of religious orthodoxy, understandable though it is, has resulted in a counterorthodoxy, supported by bad arguments, and a tendency to overstate the legitimate scientific claims of evolutionary theory. (p187)
It would be unfortunate if the Establishment Clause made it unconstitutional to allude to these questions in a public school biology class, for that would mean that evolutionary theory cannot be taught in an intellectually responsible way. (p188)
One of the disturbing things about the public debate is that scientists engaged in it sometimes write as if the idea of fundamental problems with the theory (as opposed to problems of detail in its application) were unthinkable, and that to entertain such doubts is like wondering whether the earth is flat. (p190-1)
Evolutionists often complain that questioning evolution undermines scientific progress. But it's exactly the opposite: it is the blinkered refusal by proponents of evolution to allow the theory to be subjected to scrutiny that is inhibiting scientific enquiry.