HAI Sunday 2nd Feb
Kevin Mitchell, Genetics & Neuroscience, Trinity College, Dublin
On discovering you’re an android: neuroscientific materialism and the mind-brain relationship.
Neuroscientists accept as a given that mind (soul, consciousness etc) is an emergent property of brain and no vitalist, supernatural explanation is required. The idea that they are somehow separate is usually attributed to Descartes and is probably assumed by most non-scientists and in popular culture.
Prof. Mitchell looked at various possible ways of examining this question before focusing on the scientific method of observation, hypothesis, testing and confirmation. A range of experimental approaches is possible from drugs or surgery to genetic studies and artificial intelligence. A most rewarding area has been stimulation of specific areas of the brain while examining the responses of the brain and the perceptions or movements of the subject. (These perceptions may be of any kind from memories, sounds or visual effects.) This shows that the response is specific: a given stimulus produces a reproducible response. The effects of drugs or surgery can be linked to the biochemistry of the brain or to the site of damage.
Kevin Mitchell also discussed the question of joining and separation of mind and brain. There are cases of twins joined at the thalamus and they have shared sensations and emotions. Contrariwise, severing the connexions between the left and right brains, allows the two halves to operate separately.
As all good scientists must, Prof. Mitchell examined possible refutations of the materialist hypothesis, such as out-of body or near-death experiences. The low oxygen in the brain in a subject near death induces virtually all of the perceptions described in such circumstances and they may occur in other pathological conditions or from drugs. (The interpretation of the sensations is a function of the subject’s culture; so a devout Christian might say that he sees a heavenly light or hear a celestial choir.)
From all this it can be concluded that the ‘immaterial‘ idea of brain function is not supported and, indeed, is not necessary to explain the observations.
The final section of the presentation looked at possible mechanisms for consciousness, decision-making and free will. This involved moving from a simple ‘reductionist’ view of the brain, where ‘bottom-up’ explanations are based on molecular mechanisms, to a more modern view of ‘emergent’ properties from a hierarchical system. This a difficult idea, but essentially it means that one layer of operation can communicate with a different level and influence its behaviour (see Sperry link below). Simply put, it is the connexions or organisation of a complex system that gives the outcome and not the ‘nuts and bolts’. Such a system has the possibility of being adaptable, as the brain clearly is. Add in memory and it is not a large step to thinking in terms of normative behaviour — or thinking about aims — and reflection.
It was a most stimulating presentation and the questions during and afterwards were wide-ranging, including déja vu and dreaming.
Neuroscience, young as it is, is providing valuable insights into the most important parts of our nature, namely our abilities to reflect and decide on ethical behaviour.
For those who want to explore these ideas further, Kevin Mitchell has a blog at : http://www.wiringthebrain.com/.
Sperry’s 1965 lecture ‘Mind, brain and humanist values’ is at: