I don’t quite remember when it was, though I was still quite young, but I was walking along the road thinking about things as usual and I had the sudden thought that “I” was my brain. I experienced a dizzying moment of claustrophobia imagining myself forever shut up in a box and staring out through two holes.
The moment passed, the world resumed its previous equilibrium and I continued on my way but now with a different view of my identity. I later learnt that the self-as-brain view is referred to by labels such as “materialist” to distinguish it from “idealist” or “dualist” notions that seek to place the conscious sense of self not in the body but in some other place, such as a soul.
Some materialists, though denying a soul, still try to assert the notion that “I” am not merely my brain but a composite being, a brain-and-body, because, they argue, the body very definitely influences the way we think and feel and to that extent who we are. It certainly does but I think we can answer this objection with the “brain-in-vat hypothesis” that I explore below.
Religious believers and mystics aside, there are those who seriously argue that we cannot simply equate brain and self. Two cases illustrate the thinking behind this. Firstly, imagine someone who wakes up one morning with absolutely no idea of who he is – his name, his occupation, where he lives – and yet who is to all intents and purposes perfectly healthy apart from total amnesia. His brain is still sitting in his skull and ticking over as it has always done expect that it no longer has any knowledge of who it is. Brain, present; self, absent.
Or consider, secondly, the case of someone who is involved in an accident and damages or loses part of his brain. Many of the cerebral functions that most of us take for granted are now missing or impaired but our accident victim still knows who he is, where he lives, who he is married to, and so on. Brain, damaged; self, unimpaired. Of course, there are degrees of damage. If our friend put a loaded pistol to his head and pulled the trigger, the self would probably vanish in a cloud of blood, goo and bone fragments. To that extent at least, brain and self coexist.
Or again, consider the “brain-in-a-vat hypothesis”. This scenario, beloved of fantasy writers and explored in the film The Matrix, postulates that you could place a brain in a bath of nutrients and connect it to an electro-chemical system capable of supplying exact analogues of the stimuli a normal embodied brain receives in daily life, and the owner of the brain would not know he was other than a fully functional human organism, operating normally in an everyday world.
If you find the “brain-in-a-vat hypothesis” too much to take then look at it this way: imagine that yours is the only consciousness that exists and that the world and everything in it, including what you take to be your body and your sensations, are all figments of your imagination, that you are, without realizing it, a sort of cosmic puppeteer. It sounds mad but try proving that it is not the case. Scary thought, but it suggests that the body plays a non-essential role in your sense of self.
Another scary thought is this: medical science can cure quite a lot of disease and accident damage by replacing the defective organs, with either organic parts or prostheses. This “spare-part surgery” is becoming ever more advanced. Could it ever be possible, do you think, to repair damaged brains by replacing the missing or damaged parts? If you think not, then let me mention an article in the press recently that suggested that surgeons might soon be able to alleviate the symptoms of Alzheimer’s disease by injecting stem cells into the brain. The stem cells, adaptable little creatures that they are, would take on the role of the missing cells. The idea that we might one day be able to repair brains suddenly sounds not so impossible after all.
I am sure you see where this is heading. Could we conceivably replace the cells of the brain gradually or wholesale until the subject has an entirely new brain (that is, a brain that no longer contains any of its original cells) and yet is still the same self he was before the replacement? If not, why not? And if so, in what does this selfhood consist now that it’s original embodiment has been replaced?
Answers on a postcard, please, or – better still – the back of a £5 note. Or if you don’t have a £5 note or even a postcard, a comment will do. Then maybe we can take up the subject again later.