Nagel’s first topic is the nature of the human mind. Here the tension between the two standpoints is very clear. From the outside, I appear to be simply another of the physical constituents of the universe, composed of the same basic parts as is everything else. Perhaps physics, that seemingly most objective of sciences, can give a complete account of everything, including me. However, from the inside, I simply cannot view myself in this way. >From the inside, my connection to this hunk of matter that is my body (and brain) seems rather accidental. For some, such thoughts may inspire a Cartesian dualism of mind and body. However, Nagel argues that my concept of myself need not include all that is essential to me; while my concept of myself may be silent about my relationship to my brain, it may nonetheless turn out that I am essentially identical to my brain. Nagel is inclined to endorse this identity of self and brain; unlike René Descartes, he does not believe that the human mind is an immaterial entity that animates the body.
However, Nagel does not subscribe to any physicalist wholesale reduction of the mental to the physical. Instead, he subscribes to a “dual aspect” theory of the mind-brain, according to which a physical object, the brain, has mental features in addition to its physical features. Reality indeed has a mental aspect, but this aspect consists in a set of nonphysical features of physical objects rather than in a set of nonphysical objects. We can try to place these mental features within a more objective conception of the world, but such a conception will not be objective in a narrowly physicalist sense. For Nagel, the notion of objectivity is not exhausted by the objectivity of physics. It is an enduring theme in Nagel’s work that even a fictionally completed physics cannot give a complete account of conscious experience—that is, what it is like, what it feels like from the inside, to be a subject of conscious experiences. However, we can try to think about consciousness from a more objective vantage point by thinking about what it is to be a conscious subject in general rather than about the contents of our own private consciousnesses; the result will be a kind of “mental objectivity.”