In 2015 I was invited to write a short piece on consciousness for the magazine Aeon. The text now appears to be unavailable on Aeon, so I am reposting it here.
From the moment we wake we are bombarded with stimuli. Electromagnetic radiation floods our eyes, pressure waves hit our ears, surfaces press against our skins, molecules adhere to the membranes of our noses and tongues. Our sense organs react, sending nerve impulses to our brains, where they trigger waves of neural activity, which may culminate in motor commands to our muscles (shielding our eyes from the light, for example). But something else happens, too. We have conscious experiences. We see a bright light, hear a scream, feel the roughness of a surface. There is something it is like to detect the stimuli; each experience has a distinctive qualitative aspect — a quale in philosopher’s jargon (plural qualia). Such experiences constitute what we call consciousness. But what is consciousness for? What do qualia do?
This may seem an odd question. The answer, surely, is that qualia carry information about the world. A red visual sensation tells us there is something red present; an acrid smell tells us something is burning; a pain tells us our body is damaged. There’s a problem, however. For we could get this information without qualia. Engineers build robots with computer vision systems that can detect and classify colours, shapes, and movements with considerable accuracy. They don’t need to give the robots qualia. Indeed, sometimes we behave in a robotic way ourselves. Most drivers have had the experience of driving absentmindedly, without paying attention to the road. Yet during these spells we must still be taking in visual information or we would crash. Or consider blindsight, a condition discovered in the 1970s by the psychologist Nicholas Humphrey. Humphrey studied a macaque monkey, Helen, whose primary visual cortex had been surgically removed. By the usual tests Helen was blind, but Humphrey discovered that, with encouragement, she could detect a range of visual stimuli, and in time she was able to interact with her surroundings almost as if fully sighted. (See a video of Helen and read Humphrey’s report.) Blindsight has been discovered in humans too, and the patients confirm that, though they can accurately ‘guess’ shapes and colours, they have no conscious visual sensations.
It appears, then, that the brain can do the work of perception without qualia. So, again, what is consciousness for? In his 2011 book Soul Dust, Humphrey proposes a novel idea. He argues that consciousness enriches life. It doesn’t add information; it adds interests and goals. Qualia are wonderful, magical things, and conscious creatures enjoy having them. They relish their sensations, and this relish gives them a deeper interest in their own existence. They also project qualia onto their surroundings and take a deeper interest in them too; and they come to think of themselves as having a self, which is of great importance to them. These developments, Humphrey argues, have great survival value and explain why evolution equipped with us consciousness. (Watch Humphrey talking about these ideas.)
This may be just the change of perspective we need to understand consciousness. There’s a catch, however. For qualia are very strange things; they are utterly unlike any properties known to the physical sciences, and many philosophers argue that they are nonphysical. But there is good reason to think that everything that happens in the physical world has a physical cause. Since we are part of the physical world, this means that if qualia are nonphysical, they cannot affect us. Humphrey’s proposal threatens to be self-defeating. Qualia enrich life because they are magical; yet because they are magical they can’t affect us and enrich life!
There’s a possible way out of this, which Humphrey himself adopts. It involves another radical idea. Maybe qualia are a sort of illusion. Evolution couldn’t set it up so that brain states really have qualia, so it did the next best thing. It set things up so that they seem to have qualia when we attend to them (when we introspect). Consciousness is, as Humphrey puts it, a sort of inner magic show, in which brain states are the actors and introspection the audience.
This is a big pill to swallow, and even if you’ve gone along with the argument so far you will probably want to get off here. An obvious objection is that, when it comes to qualia, seeming is reality. If I seem to be having a sensation of red, then I’m having one. This looks like a knock-down objection, but maybe we can edge round it. Here’s the idea.
Cognitive science sees the mind as a representational system, a system that records information about the world in a sort of internal code and uses this information to guide behaviour. On this view, for us to be aware of anything, our brains must represent it. This goes not only for external properties accessed through the senses (which can be represented in a robotic, blindsighted way), but also for internal properties accessed through introspection. Even if our brain states did have qualia, our brains would have to represent these qualia in order for us to be aware of them. Unrepresented qualia would be no more to us than unheard sounds. But representations are not always accurate — sometimes our brains misrepresent things. Indeed our surroundings might be set up precisely to induce such misrepresentation. A prankster might use scenery and video projections to trick a person into thinking they were seeing things they weren’t. And maybe evolution has pulled a similar trick on us — setting up our internal landscape so that introspection represents it as illuminated with magical, nonphysical qualia. Of course, it doesn’t seem that qualia are an illusion, but it wouldn’t if evolution has done its work well.
This is counterintuitive, but is it more so than the view that consciousness does nothing? It is very plausible to think that consciousness transforms the lives of the creatures who possess it, but maybe it is a transformation that can be wrought only by trickery.
Originally published in Aeon online magazine, 25 June 2015.