The common sense view of consciousness is dualism, which says that a person combines two fundamentally different things, a body and a non-material mind – a soul. Dualism is increasingly rare among psychologists, neuroscientists, and even philosophers, but it is by far the most popular view of mind worldwide. Of the 7 billion people in the world, 6 billion are adherents of religions that believe in an afterlife. Christians, Muslims, Hindus, Buddhists, and members of many other religions believe that you do not die when your body dies, but can survive after death because your soul goes on. If survival after death actually happens, then consciousness has to be something nonphysical rather than the result of brain mechanisms.
Refuting dualism requires developing a biologically plausible account of how the brain becomes conscious. The distinguished French neuroscientists Stanislas Dehaene has an excellent new book, Consciousness and the Brain, which presents an impressive array of evidence to support his view that consciousness is the global availability of information encoded and broadcast in a neuronal workspace. He does not explain, however, why particular information gets broadcast or how it results in the experiences everyone has of feelings like pain, emotions, colors, and tastes.
Terry Stewart and I have just published a paper called “Two Theories of Consciousness” that answers such questions by appealing to Chris Eliasmith’s powerful idea of semantic pointers. A semantic pointer is a special kind of neural representation – pattern of firing in a group of neurons – that is capable of operating both as a symbol and as a compressed version of sensory and motor representations. For example, people’s neural concept of chocolate unpacks into sensory representations of sweetness, texture, and so on, while allowing the semantic pointer to figure in inferences such as that you should not eat much chocolate because it is a kind of candy. Semantic pointers are formed by binding together simpler representations, where binding is a neural process that compresses information into a more compact form suitable for manipulation.
The new paper defends the following hypotheses:
H1. Consciousness is a brain process resulting from neural mechanisms.
H2. The crucial mechanisms for consciousness are: representation by patterns of firing in neural groups, binding of these representations into semantic pointers, and competition among semantic pointers.
H3. Qualitative experiences result from the competition won by semantic pointers that unpack into neural representations of sensory, motor, emotional, and verbal activity.
Support for these claims comes from their implementation in a computational model that successfully simulates many important aspects of consciousness. It should be possible to integrate this account with Dehaene’s by showing how winning a competition can automatically broadcast information from semantic pointers across numerous brain areas.
We contrast the semantic pointer competition theory with a very different claim that consciousness is not just a brain process but rather a general process of information integration that can be captured by a mathematical formula. This theory, developed by Guilio Tononi and endorsed by Christof Koch, is a form of panpsychism because everything integrates information to some extent. Brains do it better, but even an electric switch can have a small capability to integrate information and thereby be conscious. I think this view is fraught with philosophical, biological, and mathematical problems.
So does consciousness operate in souls, in brains, or in anything that integrates information? From my perspective, the brain answer is winning out, but there is still much research needed to show that neural mechanisms can explain everything that matters about consciousness.