The mind boggles

The Independent 7 June 2006 (Independent Extra p 8)

Consciousness is said to be “one of the last great mysteries for science”. It is at once the most familiar thing in the world – I imagine you are having conscious experiences right now – and the most difficult to explain. Oddly enough the great successes of modern neuroscience only seem to make consciousness itself harder to understand.

The central mystery goes back through thousands of years of philosophy; it is that the universe seems to contain two completely different kinds of thing. On the one hand are bodies and brains – physical objects that we can touch and measure and investigate: on the other are conscious experiences – private and subjective feelings that we cannot get at directly. We can ask people what they are experiencing, record their words, and measure what happens in their brains, but somehow this doesn’t seem to capture the “what it’s like” of subjective experience.

Right now for me the sky is a very faint pale blue streaked with early morning wisps of delicate pink. But how can science measure this? We can’t even tell whether you and I are having the same experience when we both say we are seeing blue. My pale blue might be your bright orange. This “what it’s like for me”, these blue and pink experiences, are what philosophers call “qualia”; the intrinsic properties of the experiences themselves. So the mystery is this – how can a couple of pounds of squishy living neurons inside a bony skull create qualia? How can electrical signals in a brain give rise to a world experienced by me? No one knows.

No one knows, but at least they are arguing about it now. When I started my research, over thirty years ago, no serious scientist would even admit to an interest in consciousness, and I was very much on my own. I had had many strange experiences and was obsessed with trying to understand them, but the science simply wasn’t there to do the job. Then gradually I found I was in the midst of a hot topic. Brain scanning and other advances in neuroscience meant we could at last peek inside a living brain, but how could we find consciousness there? The problem really got me hooked, and so I gave up my university job to read everything I could on the subject and write a textbook; a project that took me several years, leaving me very well informed but even more baffled. Everyone seemed to disagree. So I decided that I needed to ask the experts what they really meant – face to face – and that is what I did. I travelled the world talking to some of the worlds finest thinkers and put together this book of our “conversations on consciousness”.

King of the mystery is the young Australian philosopher David Chalmers, instantly recognisable with his blue jeans and long brown hair. I caught up with him in Tucson Arizona where, for many years, he has organised the famous “Toward a Science of Consciousness” conferences. He told me about his very first conference in 1994, back in the days when consciousness was still a taboo subject. He planned to give what he hoped would be a deep philosophical lecture, prefaced by a few simple remarks. No one remembers the difficult part but everyone remembers the beginning. He said that scientists doing research on vision, memory, thinking or emotions were just tackling the “easy problems”. Even if they solved all those there would still be something else left to explain – consciousness itself – and this he called the “Hard problem”.

The name stuck, and now Chalmers’s hard problem has become something of a Holy Grail for consciousness studies. Scientists and philosophers are falling over each other to become the one who solves the hard problem. The trouble is, no one knows how to set about solving it, or even what to look for.

At one extreme are those who think we need a revolution in physics to solve it, such as the flamboyant Tucson anaesthesiologist, Stuart Hameroff. “Every day” he told me “I put patients to sleep and wake them up and it’s still incredible. You wonder – where do they go?”. He has teamed up with the British mathematician, Sir Roger Penrose, to argue that the brain is a quantum computer and the conscious self depends on quantum effects in the microtubules – tiny tubular structures inside every cell of our bodies. They are convinced that this is the way forward, but no one else I talked to shared their enthusiasm.

Far more common are the neuroscientists who think that if we just get on with the “easy problems” we’ll eventually solve the hard one. Pre-eminent amongst these is Francis Crick, who won the 1962 Nobel prize for discovering the structure of DNA. After nearly half a century of biology, and at the age of sixty, he changed tack completely – turning his attention from the mystery of heredity to that of consciousness.

At the age of 88 and in failing health, he invited me to his home in Southern California, and even rearranged his chemotherapy so as to be at his sharpest for our discussion. And that was very sharp indeed. Within minutes he had turned the tables on me and was demanding that I come up with a crucial experiment. When I tried my best he dismissed it out of hand. “I think all that’s nonsense” he said “because essentially it’s purely psychology and you’re not talking about neurons.”

Crick had no time for the speculations of psychologists or philosophers – all they do is argue, he said, and they never make any discoveries. What we need to do is put the hard problem aside and get on with studying the neural correlates of consciousness; that is, measure what is going on inside the brain when someone is having a conscious experience. In this light he, and his long-time collaborator Christof Koch, were looking for the consciousness neurons – the critical parts or processes in the brain that are active when someone has a conscious experience.

He likens the hard problem to an ancient conundrum – the nature of life itself. Back in the nineteenth century, biologists were convinced they would find the special “life force” or “Élan vital” that breathed life into plants and animals and departed at their death. Of course no such force was ever found, Crick himself contributing to its demise. The answer turned out to be that when you understand how living things work you realise that they don’t need any special force at all. Will it be like that for consciousness?

The same analogy was used by Pat and Paul Churchland, a remarkable couple who are both professors of philosophy at the University of California, San Diego. They take a very strong line on Chalmers and his hard problem. “His presumption strikes me as ridiculous.” said Pat over bagels and coffee by their living room fire “I don’t see how you can tell, by looking at a problem, how difficult it is. There are lots of examples where people were convinced that one problem was unsolvable, while some other problem was trivial, and they turned out to be wrong about both.”

For the Churchlands, there is no separate “mystery of consciousness”; when we really understand how the brain’s visual system processes colour information then the problem of qualia will be solved. We’ll know all we need to know to explain the blueness of the blue sky I’m looking at now.

Finally, the most extreme view is given by Tufts University professor, Daniel Dennett. He is probably the most misunderstood philosopher alive, and I was determined to get to the bottom of his revolutionary approach. His critics have dubbed him “the devil”, which seems not to bother him at all. They regularly joke that his famous book “Consciousness Explained” should be renamed “Consciousness explained away” because he denies the existence of qualia and says there is no such thing as “consciousness itself”. Dennett believes that if we start from our ordinary intuitions about consciousness then we are doomed to failure because all those intuitions are completely wrong. For example, you probably feel as though you are a little conscious self somewhere inside your head, who is the subject of the stream of experiences. This image is what Dennett calls the “Cartesian Theatre” and it cannot possibly exist. The brain has no central controller, no inner screen where the images could appear; and no one inside to experience them. There is no magic process that turns ordinary nerve activity into conscious experiences. We must, he told me, throw out all these perfectly natural, but misguided ways of thinking about consciousness. But how? Turning your intuitions inside out is terribly hard, but if Dennett is right then most of the others I spoke to are completely wrong. Quantum physics will not help one jot, and no one will ever find Crick’s “consciousness neurons”.

I would love to pop into the Tardis, jump forward a few years, and see who turns out to be right. For now consciousness looks set to remain one of our greatest mysteries.