MIND AND COSMOS: WHY THE MATERIALIST NEO-DARWINIAN CONCEPTION OF NATURE IS ALMOST CERTAINLY FALSE by Thomas Nagel
On a purely materialist understanding of biology, consciousness would have to be regarded as a tremendous and inexplicable extra brute fact about the world. If it is to be explained in any sense naturalistically, through the understanding of organic life, something fundamental must be changed in our conception of the natural order that gave rise to life. What kind of unified conception of the natural world would allow the explanation of the development of living organisms also to explain the development of consciousness? Antireductionism allows us to pose the question, but to answer it requires something more positive. And it cannot consist (merely!) in a revision of the basic concepts of physics, however radical--as happened with the introduction of electromagnetic fields or relativistic space-time. If we continue to assume that we are parts of the physical world and that the evolutionary process that brought us into existence is part of its history, then something must be added to the physical conception of the natural order that allows us to explain how it can give rise to organisms that are more than physical. The sources of physical science are not adequate for this purpose, because those resources were developed to account for the data of a completely different kind. The appearance of animal consciousness is evidently the result of biological evolution. but this well-supported empirical fact is not yet an explanation--it does not provide understanding, or enable us to see why the result was to be expected or how it came about. In this case, unlike that of the appearance of the physical adaptations characteristic of life, an explanation by natural selection based on physical fitness to survive is not sufficient. Selection for physical reproductive fitness may have resulted in the appearance of organisms that are in fact conscious, and that have the observable variety of different specific kinds of consciousness, but there is no physical explanation of why this is so--nor any other kind of explanation that we know of. To make facts of this kind intelligible, a postmaterialist theory would have to offer a unified explanation of how the physical and the mental characteristics of organisms developed together, and it would have to do so not just be adding a clause to the effect that the mental comes along with the physical as a bonus. The need for an illuminating explanation of the mental outcome pushes back to impose itself on the understanding of the entire process that led to that outcome. . . The explanation by standard evolutionary theory of the purely physical characteristics of organisms is hard enough even if one disregards consciousness. [T]he physical and functional complexity of the results imposes very demanding conditions on a reductionist historical explanation. The theory of natural selection, if it is to rely only on the operation of physical law, has to postulate that there is a purely physical explanation of why it is not unlikely that accidental mutations in the genetic material have generated the range of variation in viable phenotypes needed to permit natural selection to produce the evolutionary history that has actually occurred on earth over three billion years. Like any historical explanation, it will embody a great deal of contingency, so the particular history of life will not be explained by evolutionary theory alone. But the contingencies and their effects have to be consistent with the physical character of the theory. And to complete the link with physics, the explanation has to suppose there is a nonnegligible probability that some sequence of steps, starting from nonliving matter and depending on purely physical mechanisms, could eventually have resulted in a replicating molecule capable of all this, embodying a precise code billions of characters long, together with the ribosomes that translate that code into proteins. It is not enough to say, 'Something has to happen, so why not this?' I find the confidence among the scientific establishment that the whole scenario will yield to a purely chemical explanation hard to understand, except as a manifestation of an axiomatic commitment to reductive materialism.
