Where does consciousness come from? The traditional view, believed by the 6 billion people in the world who belong to religions that assume life after death, is that humans consists of two different kinds of things, a body and a soul. The materialist view, held by many contemporary neuroscientists and psychologists and an increasing number of philosophers, is that the human mind is the brain. On this view the mind is a purely physical system and expires when the body does.
Recently, however, there is been a revival of a less familiar position called panpsychism. Panpsychism is the claim that consciousness is not just a property of the brain, and not a property of some special spiritual kind of substance like the soul, but rather a property of everything in the universe. Even a rock or a pebble or an atom has a little bit of consciousness in it. Panpsychism has been endorsed by two distinguished neuroscientists, Christof Koch and Guilio Tononi. Why would anyone hold this view?
The main support for panpsychism seems to be a kind of argument from ignorance. It seems mysterious how the peculiar properties of consciousness such as awareness and feeling could result from anything physical. This kind of incomprehensibility, along with religious motivations, has traditionally been used to support dualism, the idea that a person consists of two separate things, mind and soul. But with the lack of any evidence for the existence of souls, and the waning of religious beliefs, some people favor panpsychism over dualism. We just can't see how it is that properties like experience and awareness could result from the mere motions of molecules. So there must be a little bit of consciousness in everything that can then sum up to the experiences found in humans.
I think that there are many flaws with this line of reasoning. It neglects the importance of emergence, which I wrote about in a previous blog post. The natural world contains many cases where wholes have properties that are very different from the properties of their parts. A water molecule consisting of hydrogen and oxygen has properties such as being liquid at room temperature that are not found in hydrogen atoms or oxygen atoms. To take a more complicated example, consider life. Atoms and molecules are not alive, but cells and single cell organisms and much more complicated plants and animals possess life. In the 19th century, it was commonly thought that life is so different from nonliving things that there must be a special property, called life force, that belongs only to living things and distinguishes them from those things that are not alive. In the 20th century, however, it became widely recognized that life is not a special property, but rather the result of many mechanisms, such as genetics, metabolism, cell division, and reproduction. Analogously, consciousness could be an emergent property of neural mechanisms.
Curiously, no one ever proposed a life-oriented analog of panpsychism, which one might dub “panlifeism”, to say that in order to explain life we must think that there are bits of life in everything that exists. The reason that panlifeism never was proposed was the rapid progress made in 20th century biology as more and more of the details of how life works at the material level became revealed. We do not yet have nearly as good an account of the biological mechanisms of consciousness that we have for the mechanisms that support life. This ignorance allows room for people to propose panpsychism as an alternative to what I think is the more plausible account that conscious minds are neural processes.
However, we only have good evidence for the existence of consciousness in organisms that have brains. I know that I am conscious because of my own experience of awareness, sensation and emotion. It is reasonable for me to extend consciousness to other people because that ascription is the best explanation of their behavior which is very similar to mine. Additional support comes from realizing that other people have pretty much the same kind of brains as me. It is then reasonable to further extend description of consciousness to other organisms that have somewhat similar behaviors and similar brain structure to those of humans, for example mammals. The neural circuitry and the behavior of mammals supports the view that their experience of pain and emotions such as fear have a lot in common with the experiences of human beings. It may be reasonable to suppose that fish feel pain as well, has been argued convincingly in a book by the Victoria Braithwaite. But there is no behavioral evidence at all that trees or rocks or pebbles or atoms have even a tiny bit of consciousness.
In contrast, consciousness is plausibly an emergent property of brains. Consciousness is not a property of individual neurons but results from the interactions of many neurons, in the same way that life results from the interactions of many molecules. I propose in a new article that the most important neural mechanisms for producing consciousness are the following three. First, there are representations such as CAT accomplished by the interactions of large numbers of neurons. Second, these representations can generate more complex kinds of representations by a process of binding, for example producing BLACK CAT. To get to the full level of representation that humans are capable of we need to have the capacity for bindings of bindings of bindings, that is representations of representations of representations, as in THE BLACK CAT CHASED THE WHITE MOUSE. Finally the third mechanism that I think is responsible for consciousness is competition, which allows only a small subset of the available information to be active in the brain as sufficiently important to win out over other representations.
It remains to be seen whether these three mechanisms are in fact responsible for the major phenomena that need to be explained by a theory of consciousness. But if I'm on the right track, then we don't need to extend attribution of consciousness all the way down to every bit the universe. Consciousness is an emergent property of special kinds of complex systems, namely large groups of neurons. Perhaps, consciousness might also turn out to be a property of other kinds of extremely complex systems, for example ones that operate in computers. But if computers ever turn out to be conscious, I suspect that it will result from having approximate analogs of the three kinds of mechanisms that I think make consciousness working human beings: representation, repeated binding, and competition among complex representations. Once this more sophisticated account of consciousness has been developed, there will no need to suppose that there is even a tiny bit of consciousness in various bits of the universe other than brains and similarly complex systems.