Late in chapter 3 of Mind and Cosmos, Nagel introduces one of the candidates for a likely solution to the problem of Cartesian dualism. This approach can be called monism or panpsychism. Panpsychism is the view that matter and mind are two different manifestations of a single unnamed substance. Nagel thinks this path offers one possible framework for an eventual solution:
“Everything, living or not, is constituted from elements having a nature that is both physical and nonphysical— that is, capable of combining into mental wholes. So this reductive account can also be described as a form of panpsychism: all the elements of the physical world are also mental.”
“A comprehensively reductive conception is favored by the belief that the propensity for the development of organisms with a subjective point of view must have been there from the beginning, just as the propensity for the formation of atoms, molecules, galaxies, and organic compounds must have been there from the beginning, in consequence of the already existing properties of the fundamental particles. If we imagine an explanation taking the form of an enlarged version of the natural order, with complex local phenomena formed by composition from universally available basic elements, it will depend on some kind of monism or panpsychism, rather than laws of psychophysical emergence that come into operation only late in the game.”
However, there is a serious problem. We have no idea how elementary particles could possess subjectivity which Nagel calls the “proto-mental” attribute. Such an understanding would be necessary in order to build a framework for explaining how individual particles could come together and form conscious organisms. The best candidate for such an explanation is quantum physics, but our understanding of quantum physics today is limited to its computational aspects. If those aspects are real, then computation only supplies part of the solution. And you would need to assume that consciousness is partly the result of computation.
There are some philosophical positions that hold that consciousness is all computation (Dennett, Kurzweil). Anyone holding such a position may be quite happy with a quantum solution since it would explain how minds could be made of matter with computational abilities. Still, one would need to work out the details of how individual particles with computational ability can be organized so that the total organism’s mind appears to be an unbroken whole. That work might be made easier by quantum entanglement, but there is very little theoretical understanding on which to build.
Quantum entanglement provides some theoretical advantage over classical computation. Quantum entanglement enables quantum information to be coded more compactly than classical information giving it the ability to reduce entropy. Low entropy is a characteristic of order. In this way, quantum computation has order producing power beyond the ordering power of classical computation. But how this could take place in biological organisms remains a mystery.
Nagel finds additional problems with panpsychism when he imagines how it might address the developmental problem of life. How did life originally arise from non-living matter and how did this proto-mental attribute of matter overcome the unlikelihood of random chemical interactions leading to life? He concludes the section on panpsychism with this pessimistic comment:
“The idea of a reductive answer to both the constitutive and the historical questions remains very dark indeed. It seeks a deeper and more cosmically unified explanation of consciousness than an emergent theory, but at the cost of greater obscurity, and it offers no evident advantage with respect to the historical problem of likelihood.”
I find myself more optimistic about the outlook for a form of panpsychism that is based on quantum physics. I think the entropy lowering capability of quantum computation will go a long way towards explaining the ordering power inherent in life and consciousness. The problem is that quantum computation does not really explain subjective experience unless you assume that subjectivity is the result of computation. And that assumption re-introduces the problem of dualism because you would need to assume subjectivity in all matter, not just living matter. As soon as you’ve assumed that subjective experience is an attribute of living matter only, then it has to be an optional attribute, introduced by something besides physical law.
Consider what happens at the moment of death of any living organism. For a brief instant, the chemical composition remains unchanged, yet life and consciousness are gone. Subjectivity as we have come to know it during life has disappeared. This would seem to indicate that subjectivity is an optional attribute of the material world, and that is dualism.
I suppose it is possible that there are subtle changes in the chemical composition at the time of death, but will those changes be sufficiently observable to clearly indicate which came first? The subtlety may be telling us how miraculous consciousness is in the first place. One can also consider the action of anesthetics which cause temporary unconsciousness. For example, ether can cause unconsciousness in humans and inactivity in the one-celled animal paramecium, yet its exact action remains unexplained.
While I think that panpsychism based on quantum physics offers hope for explaining the tremendous ordering power of life and consciousness, I do not find that it offers a complete answer to the problem of dualism when viewed from the materialist point of view. I am drawn more to the idealist point of view as a solution to dualism. No less a world-class physicist than Leonard Susskind has suggested that the universe may be like a hologram. (A hologram is a three dimensional projection from a two dimensional source. For Susskind’s analogy to hold, the universe would need to be a four dimensional projection from some external source.) Susskind is an atheist, so he will not agree with my perspective that the universe is a projection from God, but that appears to be the only view that solves the problem of consciousness and dualism.
Thomas Nagel doesn’t agree with me either. He finishes up chapter three by dismissing the theist path of an intentional power, but gives more credibility to what he calls the teleological framework. The teleological path requires that the laws of nature are “value free,” yet they proceed toward a defined purpose or goal. Nature’s laws would need to be “value free” to avoid the appearance of an intentional designer. He needs to say more about how a desired goal can be free of value, and he promises to do so later in the book.