The Meme Machine (41 page)
Dualism is tempting but false. For a start no such separate stuff can be found. If it could be found it would become part of the physical world and so not be a separate stuff at all. On the other hand if it cannot, in principle, be found by any physical measures then it is impossible to see how it could do its job of controlling the brain. How would immaterial mind and material body interact? Like Descartes’ ‘thinking stuff, souls, spirits and other self–like entities seem powerless to do what is demanded of them.
Nevertheless, a few scientists have developed dualist theories. The philosopher Sir Karl Popper and neuroscientist Sir John Eccles (1977), suggest that the self controls its brain by intervening at the synapses (or chemical junctions) between neurons. Yet as our understanding grows of how neurons and synapses work there is less and less need for a ghost to control the machine. Mathematician Roger Penrose (1994) and anaesthetist Stuart Hameroff (1994) suggest that consciousness operates at a quantum level in the tiny microtubules inside the membranes of neurons. Yet their proposal just replaces one mystery with another. As the philosopher Patricia Churchland (1998, p. 121) observes ‘Pixie dust in the synapses is about as explanatorily powerful as quantum coherence in the microtubules’. These attempts to find a self that lurks in the gaps in our understanding just do not help, and few scientists or philosophers are convinced by them.
The opposite extreme is to identify the self with the whole brain, or whole body. This might seem appealing. After all, when you talk about Simon you mean him – the whole body, the entire person. So why not say the same of yourself? Because this does not get at the problem we are struggling with – that it feels as though there is someone inside who is consciously making the decisions. You can point to your body and say ‘that is me’ but you do not really mean it. Let us try a thought experiment. Imagine for a moment that you are given a choice (and you cannot say neither). Either you will have your body completely swapped for another body and keep your inner conscious self, or you will have your inner self swapped for another unspecified self and keep the body. Which will it be?
Of course, this is both practically and conceptually daft. Unless we can identify this inner self the experiment could not be done, and even then it implies a further self to do the choosing. However, the point is this. I bet you did make a choice and I bet you chose to keep your inner self. However daft the notion is, we seem to have it, and have it bad. We think of ourselves as something separate from our brains and bodies. This is what needs explaining, and so far we are not getting on very well.
This problem applies to any scientific theory that leaves the sense of self out of the picture. The most thorough–going reductionist view of this kind is what Nobel laureate Francis Crick calls ‘The Astonishing Hypothesis’:
The Astonishing Hypothesis is that ‘You’, your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will, are in fact no more than the behavior of a vast assembly of nerve cells and their associated molecules. As Lewis Carroll’s Alice might have phrased it: ‘You’re nothing but a pack of neurons’ (Crick 1994, p. 3).
There are at least two problems with this. First, you do not feel like a pack of neurons. So what the theory needs, and does not provide, is an explanation of how a pack of neurons comes to believe that it is actually an independent conscious self. Second, the theory does not say
which
neurons. It cannot be all neurons because ‘I’ am not consciously aware of most of what goes on in my brain; ‘I’ do not identify with the neurons that control glucose levels in my blood or the fine movements that keep me sitting up straight. On the other hand if you try to identify ‘self neurons you are doomed to trouble. All neurons look much the same under the microscope and all of them are doing something all the time regardless of what ‘I’ am doing. Crick is working on the theory that neurons bound together by simultaneous firing at 40 cycles per second form the basis for visual awareness, but this is not the same as a theory of a conscious self.
Note that this theory is more reductionist than many others. Crick not only assumes that you are utterly dependent upon the actions of nerve cells – most neuroscientists assume that – but that you are
nothing but
the pack of neurons. Other scientists assume that new phenomena may emerge from simpler ones, and cannot be understood by understanding the underlying neurons and their connections. For example, we cannot understand human intentions, motivations, or emotions just by observing the behaviour and connections of neurons, any more than we can understand the activity of a desktop computer by looking at its chips and circuits. On this more common view the
intentions depend completely on the neurons (just as the computation depends completely on the chips in the computer) but to understand them we must work at an appropriate level of explanation. But what is the appropriate level of explanation for the self? The behaviour of neurons seems to miss it.
Another approach is to identify the self with memory or personality. Victorian spiritualists believed that ‘human personality’ was the essence of the self and could survive physical death (Myers 1903). However, personality is nowadays understood not as a separate entity but as a fairly consistent way of behaving that makes one person identifiably different from another. This way of behaving reflects the kind of brain we were born with and our lifetime’s experiences. It cannot be separated from our brain and body any more than our memories can. The more we learn about personality and memory the more obvious it is that they are functions of a living brain and inseparable from it. In an important sense you are your memories and personality – at least, you would not be the same person without them – but they are not things, or properties of a separate self. They are complex functions of neural organisation.
A final way of looking at the self is as a social construction. If I asked you who you are, you might answer with your name, your job, your relationship to other people (I’m Sally’s mum or Daniel’s daughter), or your reason for being where you are (I’m the cleaner, Adam invited me). All of these self–descriptions come out of your mastery of language, your interactions with other people, and the world of discourse in which you live. They are all useful in certain circumstances, but they do not describe the sort of ‘inner self we were looking for. They describe no persistent conscious entity. They are just labels for an ever–changing social creature. They depend on where you are and who you are with. We can find out a lot about how such constructions are created – indeed social psychologists do just that – but we do not find a conscious self this way. The inner ‘me’ seems to be mighty elusive.
Where am I?
You probably feel as though ‘you’ are located somewhere behind your eyes, looking out. This seems to be the most commonly imagined perspective, though others include the top of the head, the heart, or even in the neck, and there are apparently cultural differences in this imagined position. The location may change with what you are doing, and you may even be able to move it around at will. Blind people report
feeling themselves in their fingertips when reading Braille, or in their long white cane when walking. Drivers sometimes inhabit the edges of their cars and wince if something passes too close. So is there anything actually at this imagined spot? Presumably not in the case of the stick or the car, but it still feels as though there is a self in there somewhere. Where, then, should we look for the self?
The most obvious place to look is in the brain. Drugs that affect the brain affect our sense of self, and damage to various areas of the brain can destroy or change it. Stimulating the brain with electrodes can produce changes in body image, feelings of shrinking or expanding, or sensations of floating and flying. Yet we do not feel as though we are inside a warm, wet, and pulsating organ. In a lurid thought experiment Dennett (1978) imagines his brain being removed to a vat in a life–support lab while his body roams around as usual, connected to his body as intricately as it ever was before, but by radio links instead of nerves. Now where would Dennett feel he was? As long as he could see and hear, he would feel as though he was wherever his eyes and ears were. He would not fancy himself to be inside the vat. Of course, we cannot do the experiment to check his intuitions, but it suggests the disturbing conclusion that Dennett would still imagine he was living in there, somewhere behind his eyes, even if the skull were empty and his brain were controlling things from the vat.
If we look inside the brain we do not see a self. To the naked eye a human brain looks like a lump of rather solid porridge with a convoluted shiny surface and various areas of paler or darker grey; it is hard to believe that all our thinking goes on in there. Only with high magnification and the techniques of modern neuroscience can we find out that it contains about a hundred billion neurons or nerve cells. The neurons are connected up in fantastically complex ways and, by virtue of these connections, store and process the information that controls our behaviour. However, there is no centre of action where a self might reside. There is no one place into which all the inputs go, and from which all the instructions get sent out. This is an important point, and deeply disturbing. We feel as though we are a central observer and controller of what goes on, but there is no place for this central controller to live.
Let us consider what happens when you perform a simple task. For example, find a letter ‘p’ on this page and then point to it. What has gone on? It may feel as though you have decided to find a ‘p’ (or not if you could not be bothered), searched the next few lines, found one, and then commanded your finger to move into position and touch it. The role of
the self seems obvious, ‘you’ decided to act (or not), ‘you’ moved your finger and so on.
From an information–processing point of view the role of the ‘you’ is not at all obvious. Light enters the eye and is focused on a layer of light–sensitive cells. The output from these goes into four layers of cells in the retina which extract edges and brightness discontinuities, enhance differences across boundaries, change the coding of colour information from a three–receptor system to one based on pairs of opposites, and throw away a great deal of unnecessary detail. The part–digested information is then compressed and passed along the optic nerve into the thalamus inside the brain. Here, different types of information about the image are separately processed and the results passed on to other parts of the visual cortex at the back of the brain. As the information passes through it is at some times and places coded like a map, with neighbouring positions corresponding to neighbouring locations in the world, but, at other times and places, as more abstract information about shape, movement or texture. Throughout the system there are numerous things going on at once.
From the visual cortex, outputs go off to other parts of the brain, for example, those dealing with language, reading, speech, object recognition and memory. Since you know how to read, a search identifies a letter ‘p’. Some of the information goes to the motor cortex which co–ordinates action. From here a movement such as pointing with your finger, will be pre–processed and then coordinated with visual feedback as it happens, so that the finger ends up in line with the ‘p’.
The details of this do not matter. The important point is that the description that neuroscientists are building up of the way the brain works leaves no room for a central self. There is no single line in to a central place, nor a single line out; the whole system is massively parallel. In this description there is no need for a ‘you’ who decided to find the ‘p’ (or not) and who started the finger moving. The whole action inexorably created itself, given this book with its instruction, and your brain and body.
You might think that there is still room for a central self as some kind of informational or abstract centre rather than an actual place. There are several theories of this kind, such as Baars’s (1997) global workspace theory. The workspace is like a theatre with a bright spotlight on the stage; the events in the bright spot are the only ones ‘in consciousness’. But this is only a metaphor and can be a misleading one. If there is any sense to the idea of a spotlight, it is that at any time some information is being attended to – or actively processed – while other information is not.
However, this focus of activity changes continuously with the complex demands of the task we are performing. If there is a spotlight, it is one that switches on and off all over the place and can shine in several places at once; if there is a global workspace it is not located in any particular place. It cannot tell us where ‘I’ am.
The theatre metaphor may do more harm than good to our thinking about self and consciousness. Dennett (1991) argues that although most theorists now reject Cartesian dualism, they still secretly believe in what he calls the ‘Cartesian Theatre’. They still imagine that somewhere inside our heads is a place where ‘it all comes together’; where consciousness happens and we see our mental images projected on a mental screen; where we make our decisions and initiate actions; where we agonise about life, love, and meaning. The Cartesian Theatre does not exist. When sensory information comes into the brain it does not go to an inner screen where a little self is watching it. If it did, the little self would have to have little eyes and another inner screen, and so on. According to Dennett, the brain produces ‘multiple drafts’ of what is happening as the information flows through its parallel networks. One of these drafts comes to be the verbal story we tell ourselves, which includes the idea that there is an author of the story, or a user of the brain’s virtual machine. Dennett calls this the ‘benign user illusion’. So maybe this is all we are; a centre of narrative gravity; a story about a persisting self who does things, feels things and makes decisions; a benign user illusion. And illusions do not have locations.
