by Marcus Loane
Consciousness has been accepted as a topic of serious scientific study in the last decade or two. It has been approached from a wide variety of disciplines. Biologists, neurosurgeons, philosophers, computer scientists and physicists have all been forthcoming with their speculations. New areas of discovery are always rife with speculation and this is healthy. The more competing hypotheses the better. Then we can start to think of ways to test them and narrow down the possibilities by a process of elimination.
The influences of the different disciplines are evident in the hypotheses that get proposed. Biologists tend to concentrate on evolutionary explanations, seeing the brain as cobbled together gadgetry, with the hind brain for example, being a remnant from our reptilian ancestors. Neurosurgeons concentrate on examining how neurons function and on which parts of the brain are active during different activities. Philosophers are often trapped in the past and ignore that evolutionary theory must play a role. There are exceptions such as Daniel Dennett who has made evolutionary algorithms central to his proposals. Computer scientists see the brain as analgous to computer circuitry and hope to create a conscious machine. They see the organisation of wiring and the functions it can perform as the important factors in both brains and computers. Physicists tend to oversimplify and want consciousness to be neatly described by equations rather like an electromagnetic or gravitational field.
I think the physicists are on the wrong track. Consciousness is complicated like metabolism. It is a whole set of processes which can be enabled in many ways and cannot be reduced to the simplicities of physics. We cannot have equations defining metabolism and we cannot have a precise definition of which physical arrangements of matter will cause metabolism (or locomotion or predation), ditto for consciousness. We should perhaps not think about what causes consciousness, but rather which functions and capabilities collectively are consciousness.
Another area which I think could be very promising is the study of how human brains develop in infants. After all it is there that consciousness is being "gradually turned on", and we have all been through the process "from the inside". What brain wiring is being constructed during this time? There are plenty of studies of child development but I do not know if any are addressing the issue of consciousness. I think it is (wrongly) assumed that considering babies as unconscious automatons is too outrageous to even contemplate.
With the exception of the physicist speculations and some of philosophy, there can be a synthesis of the other ideas. We should be able to get an evolutionary explanation (from biologists) which explains the neuroanatomy (explored by neuroscientists) whose functional roles may be partly replicated by computer science. There does indeed seem to be a consensus emerging. It is the idea of a global neuronal workspace (meaning the whole, or most of, the brain is involved at once). The model has been called by different names - the Pandemonium model, the Multiple Drafts model, the Ripples On A Pond model and the Spinning Scenarios model. All envisage multiple unconscious candidate thoughts (neuronal activation patterns) competing for control. The "winner" is what our conscious experience is. This is an ongoing process and new patterns replace older ones in fractions of a second. A common question here is "what happens then?" What happens then, is not some magic, but physical action: the winning patterns by being connected globally across the brain can control the body's behaviour. In other words they have the physical capability that is associated with consciousness. At any one time there are many processes occurring in parallel, vying for dominance. This may sound very metaphorical as an explanation but similar processes can be constructed in computers. The metaphorical language of the explanation can be translated into technical details of circuitry.
Now a consensus does not make an hypothesis true. Hypotheses must be tested. There have been some experiments which provide indirect evidence that we are on the right lines, but more experiments will have to be done. I hope this will accumulate over the next few decades and a theory will be established in my lifetime.
There are some who say that even after we explain the workings of the brain in minute detail there is still something we are leaving out, the inner experience, the "what it is like", qualia or some undetectable ineffable property. That is the subject of much heated debate and my thinking is that the feeling of having left something out from explanations of consciousness is itself a cognitive illusion which may eventually be explained. Both sides of the debate might agree that physical information processing structures and capabilities are necessary for consciousness*, but they disagree about whether they are sufficient. The problem for the "something extra" (soul/field/essence) proponents, is that there is nothing for the something extra to do. The hypothetical something extra makes no difference to explanations of altered inner experiences due to brain damage or ingestion of drugs or any other scenario we can think of. The sort of explanations for these phenomena will always be in terms of brain structure and function.
* Consciousness is supervenient on physical processes.
[Supervene: to be dependent on a set of facts or properties in such a way that change can occur only after change has occurred in those facts or properties.]