If you could put your brain in a nutrient bath so that it could keep on functioning outside of your body what would it (or would it still be you) experience? Would it still have your memories in it? Would it remember that they were yours? Would it still experience itself as you? Would you experience yourself as it?
This image of a free-floating brain is one that occupies the imagination of neuroscientifically aware philosophers and philosophically minded neuroscientists everywhere. Human understanding about how the brain functions grows seemingly everyday. And as it does so the idea that our experience of the world exists exclusively in our brains gets stronger – at least in the eyes of some.
If we want to uncover the philosophical roots of the notion that the world exists in our heads we can go back to Rene Descartes. Descartes can be identified as the point of origin of what we would recognize as modern philosophy. He was a scientist and mathematician who questioned what was real and attempted a daring experiment in radical skepticism.
Descartes sat down, on his bed I have been told, and decided to doubt everything so that he could find whatever it is that he could be absolutely sure of and then build up a picture of reality from there. His famous treatise called The Meditations is his account of his thought process in this experiment.
One line of inquiry that he followed rested on the common experience of dreaming. In dreams we experience the world and ourselves very convincingly. While we lie in bed asleep and unconscious to the ‘real’ world we are running around and acting in the ‘dream’ world as our ‘dream’ self. And so Descartes wondered if his experience of waking reality and waking self might also be a kind of dream created in his mind. This line of thinking is so common to us today that almost every young child has had this thought at one time or another. And it is hard for us to recognize how far out a thought this was when it occurred to Descartes in the 16th century.
One of the conclusions that Descartes came to was that reality was split into two realms – a realm of inner experience or mind, and a realm of outer extension or matter. This split between mind and matter, inner and outer has become so habitually how we see the world today that it is hard to imagine that it was at one time a novel idea.
Almost any thoughtful person today wants to distance himself or herself from this split which is commonly called Cartesian dualism. Fast-forwarded a few hundred years, sprinkle in a scientific revolution or two and you come to the controversial understanding held by many and refuted by many others that our entire experience of reality exists entirely in our brains. What we experience as the world and as ourselves is simply a bi-product of electoral impulses in our brains. And confidence in this view increases as modern neuroscience proves ever more convincingly that understanding the neurological activity in our brains explains how our experience of reality is created.
Now back to the Saturday afternoon horror movie image of a brain in vat. A brain that is removed from its original body in such a way that it continues to experience and think about the world. This image brains in vats is worth thinking about because reveals some deeply ingrained assumptions about reality and a whole host of problems with those assumptions. Two recent books that I have read both use this image although from somewhat opposing points of view. One is Thomas Metzinger’s The Ego Tunnel that I mentioned in my last post and the other is Alva Noe’s book Out of Our Heads that I read a couple of years ago and has become a favorite of mine. I will explore both Metzinger and Noe’s points of view in my next post. And eventually I want to loop this all around to a discussion about William James’ views from over a century ago that is a precursor to this whole discussion.