Thomas Nagel in the NYT's in The Stone:
The scientific revolution of the 17th century, which has given rise to such extraordinary progress in the understanding of nature, depended on a crucial limiting step at the start: It depended on subtracting from the physical world as an object of study everything mental – consciousness, meaning, intention or purpose. The physical sciences as they have developed since then describe, with the aid of mathematics, the elements of which the material universe is composed, and the laws governing their behavior in space and time.
We ourselves, as physical organisms, are part of that universe, composed of the same basic elements as everything else, and recent advances in molecular biology have greatly increased our understanding of the physical and chemical basis of life. Since our mental lives evidently depend on our existence as physical organisms, especially on the functioning of our central nervous systems, it seems natural to think that the physical sciences can in principle provide the basis for an explanation of the mental aspects of reality as well — that physics can aspire finally to be a theory of everything.
However, I believe this possibility is ruled out by the conditions that have defined the physical sciences from the beginning. The physical sciences can describe organisms like ourselves as parts of the objective spatio-temporal order – our structure and behavior in space and time – but they cannot describe the subjective experiences of such organisms or how the world appears to their different particular points of view.