I am told that everything we see, hear, feel, smell and taste is filtered through our brains and that without brains we would feel nothing. What we are conscious of is not the direct, unmediated world but our brain’s representation of the world.
If this is true then the difference between wakefulness and dreaming is that during wakefulness our thoughts are constrained by reality whereas when we are asleep they are not. In both cases we are looking at the brain’s representation of things rather than directly at the world.
In one sense it is obvious that our brains are filtering what gets through to us (‘us’ being our conscious selves). There is clearly too much happening out there in the world for us to take in. Our brains would have to be the size of beach balls to deal with all the incoming data and even then they wouldn’t be big enough. And even if they could, how could we think straight with all that data available?
Brain surgeons can open up a person’s head and by stimulating different parts of the brain make them smell bacon or taste honey, even when there isn’t a pig or bee in sight. This shows that the brain is constructing its own reality based on (usually) reliable information from the world outside.
Yet simply because you can trick a person into thinking that he can smell bacon by cutting open his cranium and poking his brain in the right place does not mean that he is always tricked, any more than a mirage of water in a desert suggests that water is always imaginary.
Even if it is true that we never get to know the outside world directly this hardly matters. After all, a snake bite is deadly whether the experience of being bitten is mediated through the brain or not. Since the brain in its wakeful state gives us a workable (though incomplete and sometimes inaccurate) representation of the world outside, why should we care whether reality comes to us first or second hand?
Knowing that what you are experiencing is all in your head (though strongly influenced by what is happening outside your head) can induce either a feeling of claustrophobia or of security. You can feel trapped in a solipsistic world, as Bertrand Russell did by the thought of the world existing only in his head, or you can feel safe in your own world: it is all happening in your head so it is your world, your snake bite. Your consciousness never directly touches the alien weirdness that exists outside you.
Paragraphs like the one above lead some people to believe that since we only ever experience the world through our brains and our brains are good at fabricating illusions – as we know from dreams – then maybe the real world doesn’t exist at all. Maybe we are disembodied consciousnesses floating around in space just dreaming the whole thing.
This is nonsense. Just because we invent worlds unconstrained by reality in our sleep doesn’t mean that we do the same when we are awake. This, after all, is why we have two words, ‘awake’ and ‘asleep’, to differentiate between the two states.
But don’t worry, you can actually do a test to demonstrate the difference. Try dreaming about falling from the top of an industrial chimney, as I did a few months ago. You will be relieved to find that you are still alive and well in the morning. Now try climbing to the top of a real industrial chimney and throwing yourself off while you are awake. I think you will find that you don’t wake up ever again. This distinction should be clear enough for even the weirdest of mystics.