One of the arguments against the theory of evolution is that the theory cannot account for the existence of consciousness. No mere essay such as this one could possibly do justice to the mind/body problem, and it must be that extra cup of coffee I had this morning that has led me to this presumption. However, there is one feature of the debate over the nature of consciousness that I believe is worth calling attention to, even if only in an oversimplified manner, as necessitated by the limitations of space.
The theory of dualism typically attributes to consciousness and matter radically opposite properties. Among other things, consciousness, thought of as the essence of the mind or the soul, is associated with that which is alive, aware, and active, whereas matter is said to be lifeless, insensible, and passive. Because mind and matter are thought of as distinct substances that interact with each other, it is easy to imagine that the mind or soul can survive the body. This is most agreeable with religious notions of immortality. As such, whereas matter is part of nature, the conscious mind is supernatural and destined for some kind of afterlife. Needless to say, on this dualistic understanding of mind and matter, material evolution cannot possibly explain the existence of the immaterial soul. And thus it is that the existence of consciousness is often put forward as an objection to the notion that the theory of evolution is sufficient to fully explain life, especially the existence of man.
In response to this, a lot of atheists argue that consciousness did evolve, that it is an emergent property of matter, arising when a certain level of complexity is reached. They may admit that they are not sure exactly what level of complexity is required, or at what point in the evolution of life consciousness emerged, but emerge it did. Such a position essentially accepts the conception of matter as formulated by the dualists: it is lifeless, insensible, and passive. We might be able to understand how complexity of such matter could eventually produce animal life, but it is hard to see how mere complexity could ever bring about sensation or feeling from such an unpromising beginning.
There is no need to accept this conception of matter as laid out by the dualists, however. In fact, since the dawn of philosophy, a lot of materialists have realized that in order to materialize consciousness, matter must be spiritualized. Thales, the first pre-Socratic materialist, said that all things came from water. To this assertion that everything evolved, if you will, from a material element, he added that “things are full of gods.” Lucretius, another materialist, said that in addition to properties such as size, shape, and weight, atoms also had “inclinations.” Thomas Hobbes, in elaborating his theory of materialism, explained the motion of bodies as resulting from an “endeavor.”
In other words, instead of arguing that consciousness emerged from matter as a result of complexity, one can argue that it was there from the beginning. Of course, if we are going to attribute consciousness to matter in its simplest forms, in an electron for instance, it must be consciousness in its simplest form as well. Some people strongly associate consciousness with intelligence, but electrons are clearly not intelligent. For others, “consciousness” means self-awareness, but that also lets out electrons. At most, an electron can be thought of as having something like a feeling or an urge.
If we decide to accept a notion of matter that is conscious, we have a choice to make between interactionism and parallelism. Referring again to the metaphysics of Lucretius, inclination was a property that atoms had alongside material properties, such as size, shape, and weight. Whereas the material property of weight made the atoms fall straight down, in his view, the inclination of the atoms could make them swerve. And this inclination was the basis of the will in man. In other words, he had an interactionist view of things. Material properties of atoms would have them do one thing (fall), while the mental property, the inclination, would have them do something else (swerve).
The problem with this understanding of things is that it seems to be the same old dualism of mind and body shrunk in size to that of the atom. Alternatively, there is the idea of parallelism, known as the dual-aspect theory. To go back to the example of an electron, its mental aspect, be it a feeling or an urge, is not a property distinct from its mass and electric charge. Rather, the feeling it has is the “inner nature” of the material properties, the way the mass and charge are experienced by the electron. Under this view, there are no Lucretian swerves. If an electron swerves, we can attribute that swerving to such things as an electric or gravitational field, with some kind of sensation present paralleling that swerve.
The first philosopher to propose the dual-aspect theory was Spinoza, whose writing, unfortunately, is more mediaeval than modern. Schopenhauer is my favorite exponent of this view, although his philosophy is bound up with Kant’s transcendental idealism, which I have never been able to fully understand. And if I read him right, Shadworth Hodgson, who is mostly known as being the first epiphenomenalist, also espoused a version of this theory. With regard to the last two philosophers, we may discern a debate as to which is causally determinative, the mental or the physical. In other words, just who wears the pants in this universe? For Hodgson, it was the physical. He compared consciousness to the color of the stones on a mosaic, whereas the stones themselves and the cement that holds them together correspond to physical reality. Schopenhauer, on the other hand, opted for the will as being causally determinative, with physical reality being just the outer appearance of the phenomenon of the will.
But to ask which of the two, the mental or the physical, is the more important is like asking of a coin dropped into a slot to buy candy, which was the more important, the head or the tail. Keeping with the coin analogy for a moment, imagine seeing coins on a table, all of which are Indian Head nickels with a buffalo on the back, some of which have the Indian head facing up, with others having the buffalo facing up. If we had never seen this type of coin before, and we had no way of turning one of them over, we might never suspect they were the same coin. In a similar way, when we look at a stone, we cannot see its mental aspect, and when we feel a pain, we cannot see its physical aspect.
The head of a coin and its tail never interact. If we toss a coin in the air, the head and tail move together in parallel, neither one being determinative of the motion of the other. On the other hand, coins interact with each other. If we move those hypothetical coins around on the table, still ignorant of the fact that they are the same type, we might see an Indian bump into a buffalo and cause it to move, and we might see elsewhere a buffalo bump into an Indian and likewise cause motion, leading us to conclude that there is interaction between Indian Head nickels and Buffalo nickels as distinct kinds of coins. In reality, the interaction is between a single kind of coin, viewed differently.
In a similar manner, we know there is a correlation between pain and brain states. A dualist will say the brain state, which is physical, causes the feeling of pain, which is mental. In reality, the brain state and the pain are two aspects of a single thing. In asserting this identity, I am not saying that the mental aspect of this brain state is identical with its physical aspect, any more than I would say that the head of a coin is identical with its tail. Rather, just as a coin with an Indian head on its obverse side can be identical with a coin with a buffalo on its reverse side, so too can a brain state, observed as physical from the outside, be identical with a brain state, felt as pain from the inside. In this regard, identity theory is in agreement with the dual-aspect theory, the difference being that most identity theorists believe that such identities are limited to nervous systems, which is a version of the theory that consciousness emerges when there is sufficient complexity, whereas the dual-aspect theory assumes such identities in even the simplest forms of matter.
The dual-aspect theory is not a popular one, and has few proponents. The main reason, I believe, is that it is counterintuitive to say that matter in general has a mental aspect, and so much so that to advocate such a theory is to open one up to derision. It is in the opposite situation from dualism, which appeals to our intuition and common sense. And most of us speak the language of dualism, for it is easily understood and allows for brevity of expression.
My pet theory aside, the main point I wanted to make in all this is that in debating the theory of evolution with those who say the theory cannot explain consciousness, we need not resign ourselves to accepting the impoverished conception of matter provided by dualism, but may avail ourselves of an enriched version more suitable to our needs. The longer we delay the moment in which consciousness makes its appearance in this world, the more we implicitly concede that there is something mysterious and inexplicable about it. Better to embrace consciousness as present in matter from the beginning, thereby completely naturalizing it.