The nature of consciousness is considered one af the 'hard' philosophical questions. There have been plenty of books written on the subject, but the ideas on what it is don't seem to be converging towards an accepted answer. In a sense this is strange....

“How many are there?”, I enquired. “About a thousand and four” said Bruno.
“ You mean 'about a thousand' ” Sylvie corrected him, “ You can't be sure about the four ”
“It's just the four I can be sure about; 'cause they're here, grubbing under the window! It's the thousand I isn't pruffickly sure about. ”

Consciousness is the one thing that we are sure about. But it does seem very difficult, because it's how it fits in with the rest of the world that is a problem– you can't be sure what it takes for other entities to have the same experiences as you do. Below I've listed the main contenders for the rôle of explaining consciousness, without lapsing into mysticism that is. So lets have a look at the possibilities.

Another problem is that this means that everything we do could be simulated in a computer. This may not seem to be too bad, but suppose that in the future people wanted to simulate the first time you read this page - you have to admit it's a possibility. So how do you know that what you are experiencing now really is you reading this page - it's more likely that its a simulation of it in the future.

This says that what we call mind can be explained by physical causes. The more extreme version says that consciousness is an illusion, but that's silly because it implies that consciousness is a valid concept, just we don't have it. Physicalism says that all our experiences are simply the result of the activity in our brain, and could just as well be experienced or simulated by a computer. Thus it would be possible to have a computer program which experienced pain for example. The problem with this is that then we could break up the system into smaller modules which individually did not experience pain, and then connect these together by some other method - we could suppose that people undertook some of the work (This is a variant of the Chinese Room argument). Then supposedly the pain is still there, but it is difficult to see where - certainly the people involved aren't experiencing it.

This is the idea that mind and matter are separate entities. It was put on the map by Descartes but has rather fallen out of favour recently. Interestingly it is criticised from both sides - some people say it's too mystical, others say it's too materialistic. Dualism is excluded if you accept the popular notion that the physical world is causally closed. However I feel that this doesn't really have any supporting evidence. No-one has confirmed that there is nothing extra happening in your brain to what can be predicted by the laws of physics. As I see it the real problem with Dualism lies elsewhere....

If we are to avoid mysticism, then we can assume that a separate consciousness-stuff might be discovered. We can compare the theory of consciousness to that of time. Before Einstein there was lots of philosophising about time, but it was only really after relativity was discovered that time became something which could have a theory about its properties. It could be the same with consciousness – we could build up a theory about this consciousness-stuff . Then it would have the same status as other laws of nature. A success for Dualism? The trouble is that we are then back where we started! If we built a machine which simulated this theory of consciousness then we would still have the question of whether we could call this machine conscious, or whether it lacks the 'inner experience'?

This is the idea that mind is something separate from matter, but is unable to influence it. Can you imagine a world exactly like the one we live in, except that the beings in it are not conscious – a so-called zombie world? Then our consciousness must be something extra to the physical world, an epiphenomenon. This is quite a popular view nowadays, certainly more popular than Dualism. I find this strange because, as I see it, Parallelism is a non-starter. Parallelists would ask us to believe that the books they write describing their inner experiences are nothing to do with their inner experiences, but just the mechanical action of their bodies - and yet the inner experiences are still supposed to be there. I can't take that seriously.

In the above the status of matter is at least as great as that of mind. Idealism says that mind is the predominant entity, and that nothing exists unless we perceive it. Some forms of quantum philosophy take us this way. The trouble with this is that it has proven impossible to separate it from mysticism. It was partly to escape from the mystical nature of idealism that Cartesian dualism was born. I have to say that if someone came up with a non-mystic version of idealism then, given the problems with the other views, I would consider it a very strong contender.

Of course there are other things to consider when thinking about consciousness. One idea is that of panpsychism – it is not just brains that are conscious, everything is. This sidesteps the problem of explaining why some things are conscious and some not, but it leads to questions such as "If you stick a pin in your finger does your finger feel pain as well as you? On the whole Panpsychism is difficult to make sense of and inevitably leads to mysticism.

An important question for all of us is what happens to our consciousness after we die. Physicalism says that it disappears, but if we accept that our memories are stored in our brains then other ideas aren't really much more encouraging. It is hard to conceive our consciousness surviving without our memories, so something more is required for the typical life after death scenarios.

I think the conclusion to be drawn from this is: Yes there are questions to be answered about consciousness, and there is much more work to be done on the subject, both scientific and metaphysical. However, we shouldn't criticise the scientific work if it doesn't answer the hard question of what consciousness actually is, and we should only expect the metaphysics to map out the area, rather than to provide a final answer.