WE intuitively believe that what we see is what there is. Despite philosophers like Kant and Schopenhauer telling us that it is actually the brain that determines how we experience the phenomenal world, it has never felt right; it still doesn’t. But how does the brain find out about the world, trapped as it is inside the dark theatre of the skull. As neuroscientist David Eagleman writes in The Brain ‘the brain has no access to the world outside’. He adds: “Sealed within the dark, silent chamber of your skull, your brain has never never directly experienced the external world, and it never will.”
So the brain relies on sensory organs to pick up information carried by photons, air waves, molecules, texture, and temperature, which it then turns into electrochemical signals. These in turn pass through networks of neurons. Eagleman writes: “There are a hundred billion neurons in the human brain, and each neuron sends tens or hundreds of electrical pulses to thousands of other neurons every second of your life. Everything you experience – every sight, sound, smell – rather than being a direct experience – is an electrochemical rendition in a dark theatre.” Even for those of us who are familiar with this sort of research, it remains mindboggling.
Experiencing the world as we do feels effortless. But it’s not. The brain has to put in an enormous amount of effort every second of our waking day just to see. And that’s not all, it then has to synchronize all the other senses, all of which it processes as different speeds. For example, light has to go through a more complicated process than auditory signals, which is why sprinters react quicker to the sound of a gun than to a light signal. And yet all these different processing speeds are gathered together to make it seem as though they are happening at the same time. This is because your ‘brain collects up all the information from the senses before it it decides upon a story of what happens’. And before any of this happens the brain guesses what’s out there and then adjusts its internal model depending on the extent to which its expectations are met. It is, in effect, a Bayesian inference machine.
But how does all this translate into the hard problem of consciousness? How does matter become intentional? For Eagleman the answer is that consciousness is an emergent property. Now we are entering choppy waters. Not everybody is on board when it comes to emergent properties, which essentially purports to explain how consciousness emerges from a sufficiently complex nervous system. Prof Raymond Tallis, writing in Philosophy Now, for example, is unimpressed: “It is, however, becoming increasingly obvious that ’emergence’ doesn’t reduce the problem of life, even less the puzzle of conscious intelligent life. Emergence looks more like a description than an explanation.”
However, Prof Tallis does not explore further work by Prof Giulio Tononi of the University of Wisconsin, who goes beyond the emergent property model to suggest, from his studies of people while asleep and awake, that consciousness requires a perfect balance between what he calls differentiation – that is enough complexity to represent different states – and integration, which requires ‘enough connectivity to have distant parts of the network in tight communication with one another’. Eagleman comments: “In this framework, the balance of differentiation and integration can be quantified, and he proposes that only systems in the right range experience consciousness.” Prof Tallis might respond by saying that this is a just a more detailed description rather than an explanation. But is there not a point at which a description becomes so detailed that it flips into becoming an explanation? Do at least some scientific discoveries start as descriptions but in doing so are also explanations or at least involve explanation? Christian Baden writes: “The conditions and rules sustaining the explanation can themselves be described and explained, resulting in substantial overlap between description and explanation.” And maybe the balance between differentiation and integration provides the explanation of the description provided by emergence theory.
Underlying Prof Tallis’s objection to emergence theory is his resistance to the idea that the mind can be described and explained in purely materialistic terms. At present there appears to no knock-down argument for materialistic or non-materialistic explanations of the mind and consciousness. It’s true to say that materialists have got to provide definitive proof that consciousness is just a matter of matter. But that is not in itself proof that it is non-materialistic either, anymore than pointing out that science does not have, and may never have, all the answers about existence and the universe, or universes, is proof of the existence of a god. What is going for the materialist is Ockham’s Razor in that it does not require any further explanations, whereas non-materialism does.