Raymond Tallis, M.D.
3.6 Why There Can Never Be a Brain Science of Consciousness: The Disappearance of Appearance
There are many other aspects of consciousness that elude any kind of conceptually coherent explanation. For example, it is not clear how, within the population of nerve impulses, we could find the basis for the absolutely fundamental difference between the level of consciousness (alert v drowsy v comatose) and its content; between background lighting and that which is lit. And what about the active directing of attention or racking one’s brains to remember something? But I won’t pursue these problems because I think I have already given enough reasons for maintaining that not only are neural explanations inadequate but they are wrong in principle and their current inadequacy won’t be amended by technological advances enabling ever more complete accounts of what is going on the brain. These, however, are only symptoms of a fundamental contradiction in neural theories of consciousness that I want to discuss now. The contradiction vitiates the very idea that certain material events in the brain could make the world around the organism or (in the case of human beings) the person appear to that organism or that person. The materialist account of mind requires us to confer on brain events properties that actually run contrary to the physical notion the matter of which they are formed.
Let us go back to what Daniel Dennett (accurately, I believe) calls ‘the contemporary orthodoxy’ in a passage quoted in Section 1.2:
There is only one sort of stuff, namely matter – the physical stuff of physics, chemistry and physiology – and the mind is somehow nothing but a physical phenomenon. In short, the mind is the brain… We can (in principle!) account for every mental phenomenon using the same physical principles, laws and raw materials that suffice to explain radioactivity, continental drift, photosynthesis, reproduction, nutrition and growth. 62
This, the clearest possible statement of the metaphysical framework of Neuromania, shows why it is a castle built on sand. Once we look past the relentless personification of the brain and bits of the brain indulged in by neuromaniacs – to be discussed in Chapter 5 – we will see that Neuromania has to look for consciousness in material events (neural activity), located in a material object (the brain) while holding that the final truth of material events and material objects is captured in the laws of physics. The trouble with physical science, however, is that it is committed to seeing the world in the absence of consciousness; indeed, at its heart is the disappearance of appearance. This presents not one but three insuperable problems for Neuromania. They are inextricably connected but it is helpful to address them separately: the first concerns the nature of nerve impulses; the second concerns the things nerve impulses are supposed to make appear; and the third relates to the supposed capability of nerve impulses to make those things appear.
Nerve Impulses Don’t Have Definite Appearances.
Let us get back to basics. If I claimed that consciousness was identical with neural activity, then you might reasonably assume that I had a clear idea what I meant by ‘neural activity’. We have already seen that there are serious ambiguities in this concept which leaves it unclear how we should think of what goes on in those parts of the brain that are supposedly associated with subjective experience. Is ‘neural activity’ something that is delivered to a certain place in the brain? Or is it the sum total of what is happening in several places of the brain? If so, where is the summing and the totalling taking place? Does consciousness reside in the travelling of nerve impulses along neurons or its arrival at a synapse? These questions invite a closer look at what we think a nerve impulse is. In trying to think about this we run into an immediate difficult, one that we glossed over in chapter 1, when we described nerve impulses: that of trying to get clear about what a nerve impulse is in itself.
You may think that that had been spelled out in (fairly pitiless) detail in Chapter 1. It will be noticed, however, that the nerve impulse could be described in different ways. Here are some:
a) the instantaneous passage of sodium and other ions through the semi-permeable membrane that surrounds the axon of the nerve fibre leading to an alteration in the potential difference across the membrane at the point of passage;
b) a pattern of events taking place at a particular point on the membrane that occurs over a time of the order of milliseconds and is represented by a wave or a spike traced on an oscilloscope screen – in other words, the sum total of the changes in the potential difference across the membrane;
c) the overall journey of the wave along the length of the nerve axon – a propagated displacement of the alterations in the potential difference along the length of the axon – a displacement of a displacement;
d) a part of a summed total of many millions of nerve impulses as seen on an EEG or inferred from an fMRI scan.
Since the nerve impulse may be represented with equal validity as being any of these thing, it is intrinsically none of them. The properties that are ascribed to them – being a passage of ions at a particular place, being a wave at a point on the axon, waves, being the journey of a travelling wave (and by this means binding together different places in the brain), or adding up to macroscopically visible activity occupying certain quantities of brain tissue at a certain intensity – are observer-dependent.
To put it slightly differently, there are different ‘takes’ on a nerve impulse. It could be seen as an influx of sodium ions at a particular point in the neuron followed by an efflux of said ions. Or as a change of the potential difference between the inside and the outside of the membrane at a particular place. Or as a succession of events, lasting about a millisecond, at a particular point in the neuron. Or as a wave of activity at that point. Or as a wave moving along the neuron. Or as a wave arriving rather than travelling. Or as one of a crowd of waves, several thousand, several million or several billion strong, occurring in a particular place in the brain. There are many other candidates – for example patches of coloured pixels in brain scans or brain maps. But I hope the point will have been made: the appearance of a nerve impulse depends on how it is looked at. It is not in itself a local passage of sodium ions or in itself part of a billion-strong crowd of waves, otherwise it would have to be both of these at the same time.
And it is not just a matter of how the impulse appears. What a nerve impulse is depends upon how it is viewed. A micro-pipette recording from a single neuron will deliver a different account of a nerve impulse compared with an EEG recording large-scale activity through the skull. Or, to draw the conclusion that should be blindingly obvious to anyone who is not ideologically wedded to Neuromania, the nerve impulse does not have any intrinsic determinate appearance or character. It depends how it is looked at, on how it is teased apart or put together. We are deceived if we think that scientific instruments reveal what it looks like ‘in itself’. It is easy to overlook this when we confuse the representation(s) of the nerve impulse with the thing in itself. We are less likely to do so if we remind ourselves that there are many competing ways of representing a nerve impulse. Some of these representations see the impulse as extended over time – as for example when it is envisaged as propagating along the length of the neuron. Temporal depth, as we have just discussed, is not to be found in matter – or in material events such as nerve impulses. The nerve impulse requires a viewpoint (provided by a highly mediated consciousness involving sophisticated scientific instrumentation) to be either an instantaneous displacement in potential difference at a particular point in space and time; or a spike extended over a short time at particular place; or a spike moving over space and time; or a member of a crowd of spikes moving over space and time and spreading over space and building up over time.
Anyone who still thinks that neural activity has an intrinsic appearance that is independent of observers might want to reflect on this final twist. Some of the ways we may represent nerve impulses to ourselves can be analysed into two or more takes that correspond to incompatible viewpoints. For example, seeing the impulse as a travelling spike requires a observation over time at a particular place (this generates the image of the spike) and observation at successive places.
Material Objects Do Not Have (Phenomenal) Appearances When Viewed Through the Eyes of Physics.
Nerve impulses are not uniquely impoverished in having no intrinsic appearances. This lack of intrinsic appearance is evident throughout the material world as seen through the eyes of physical science. This was noted early in the history of modern science. Galileo - and subsequently philosophers such as Descartes and John Locke – marginalised most of the things that make up the appearance of material objects as being (mere) ‘secondary qualities’. Colours, tastes, smells, sounds and so on exist only where there are observers and they do not correspond to what, according to physical science, is objectively there. As Galileo said, ‘If living creatures were removed, all these qualities would be wiped away and annihilated’ 63. The material world has only primary qualities such as solidity, extension, motion, number and shape. These by themselves would not, however, amount to a full-blown appearance. You couldn’t imagine an object without a colour (and ‘colour’ here includes black and white). Primary qualities by themselves don’t really amount to much. An object such as a cup reduced to its primary qualities would not only lack colour etc but also features such as being near or far, looking small or large, and being related to this object rather than that. Indeed, it would boil down to naked numbers which capture (abstracted) figure, motion, size and so on. This is what lies behind Galileo’s famous assertion that the book of nature is written in mathematical language. One manifestation of this view is connected with the centrality of measurement in science and the reduction of the phenomenal world to numerical quantities and the unfolding of events to the relationships between quantities, ultimately expressed in equations. The output of measurement is a number - of abstract units, or patterns of numbers of abstract units or general laws connecting numbers of abstract units.
Let’s illustrate what happens when we progress from immediate (subjective) experience to (objective) measurement with a simple example. Imagine you and are looking at a table. Because we are looking at it from different angles, it seems square to you and oblong to me and I think it is bigger than another table and you think it is smaller. We decide to settle our disagreement by making a measurement and discover that it is 3 feet by 2 feet. End of argument; but also end of the appearance of the table. It is no longer ‘square’-looking or ‘oblong’-looking. It has no secondary qualities and it lacks position and relationship to us. We have replaced its appearance by two numbers. You might want to argue that there is a residue of appearance: the appearances that are necessary to make the measurement; for example the appearance of the ruler next to the table. But of course, these appearances set aside once we have the result: ‘2 foot by 3 foot’ gives no hint of the appearance of the devices (the tape measure or ruler) by which the measurement was made or of the processes which led up to the measurement. They are as irrelevant as the quarrel we had over which side of the tape measure to use. And the actual appearance of the measurement as written down - ‘2 foot by 3 foot’ - is equally irrelevant. It would not matter whether the result was written in blue ink or black, was written as “2’ by 3’” or “2 foot by 3 foot” or “Two foot by three foot” or whether it was spoken or presented on a screen.64
We seem, therefore, to have a disappearance of appearance as we move from subjective experience towards the scientific, quantitative and ultimately mathematical account of the world as matter. This loss of appearance is strikingly illustrated by those great equations that encompass the sum total of appearances such as “e=mc2” . But is also present at a more homely level when we try to envisage material objects as they are in themselves. Think of a rock. I can look at the rock from the front or from the back, from above or below, from near or far, in bright light or dim. In each of an (innumerable) range of possible circumstances it will have a slightly or radically different appearance. In itself, it has no definite appearance: it simple offers the possibility of an appearance to a potential observer. (Though those possibilities are constrained – the rock cannot look like a bowl of custard.) So we can see that, as we get closer to the material world ‘in-itself’, as a piece of matter, so we lose appearances – colour, nearness or farness, perspective. (The history of science, which is progress towards greater generalisation is a gradual shedding of perspective – a journey towards that Thomas Nagel described as ‘a view from nowhere’.) You might want to say, it still has primary qualities. Weight, size, shape may exist independently of any consciousness, as is evident from the fact that the rock may have an impact irrespective of any perceiver. It may provide shelter to grass, stop the dampness in the soil underneath it from drying out so quickly, arrest the path of another rock rolling down the hill, cast shadows and so on. Primary qualities, however, do not add up to an appearance. A rock does not have the wherewithal to generate the way it would appear in consciousness – even less from ‘from a long way off’ or ‘from close to’. It is, of course, potentially all of these things but the potential will not be realised unless the rock is observed. If those appearances were intrinsic rather than merely potential, if they were in the rock itself, then it would be in conflict with itself, trying, for example, to look as it does from far off and from nearby at the same time. Like the nerve impulse, the rock – or indeed any other material object considered in the absence of an observer, as matter - does not have an appearance. Such appearances as material objects do have are the ‘takes’ that external observers – or an entire community of scientific observers coming to a conclusion about the way of representing impulses – have on them. While the objects provides certain constraints on ‘takes’, it does not of itself deliver takes; ‘takes’ require consciousness; indeed, consciousness is made up of takes. Material objects as viewed by physics ‘in themselves’, as matter, have no appearances. The very notion of a complete account of the world in physical terms is of a world without appearance, a world without consciousness.
Nothing in (Appearanceless) Nerve Impulses Suggests that Have the Ability to Make Appearanceless Material Things Have Phenomenal Appearances.
So far we have arrived at two conclusions: firstly, nerve impulses do not have definite appearances or character in themselves; and, secondly, they share this lack with all material items when the latter are considered independently of an observer, most obviously when see them through the mathematical eyes of physics. We are now in a position to see the inherent contradiction of trying to find consciousness in nerve impulses or, more broadly, to see consciousness as a property arising out of certain events in the material world. Consciousness is, at the basic level, appearances or appearings-to but neither nerve impulses nor the material world have appearances. So there is absolutely no basis for the assumption, central to Neuromania, that the intrinsically appearance-less material world will flower into appearance to a bit of that world (the brain) simply because of the particular material properties of that bit of the world – for example its ability to allow the passage of sodium ions through semi-permeable membranes. We cannot expect to find anything in a material object, however fashioned, that can capture the difference between a thought and a pebble, or between a supposedly thoughtful brain and a definitely thoughtless kidney. And there is even more obviously nothing in the difference between a spinal cord and a cerebral cortex to explain why the former should be thoughtless and the latter (in parts) thoughtful. The idea that nerve impulses can journey towards a place where they are consciousness implies that, by moving from one material place to another, they become able to be the appearance of things other than themselves, is nothing short of barmy. If this is physics, it is not as we know it, Jim!
The difficulty of seeing how nerve impulses confer appearance upon the material world has led some to suggest that we do not experience the world as such, only nerve impulses. But what we have said already knocks on the head this ‘last ditch’ position which, as it were, tucks consciousness back into the neural activity, making it as it were be ‘of itself’. Iain McGilchrist, whose extraordinary The Master and His Emissary represents Neuromania at its most extreme, asserts that ‘one could call “the mind” the brain’s experience of itself’ 65 and many others have suggested that consciousness is our perception of some physical processes in the brain. In short, that consciousness and appearance are made of the appearance of nerve impulses to themselves! Leaving aside the fact that nerve impulses do not have a definite appearance apart from a viewpoint which has a certain take on them, there is no reason why they should be riddled with self-awareness that is, mysteriously, awareness of the material world that is their immediate and remote cause. 66
The science within which neuroscience is framed is ultimately physical science that sees both the observed object and the brain as material entities. Matter itself, by definition, ex officio as it were, does not have an appearance corresponding to the kind of things we experience in consciousness. No more does energy. There is nothing in either corresponding to my seeing my red hat. The light-mediated rubbing together of an appearance-less object (my brain) with appearance-less light arising from an appearance-less object (my hat) is hardly going to explain the appearance of my hat to me, the owner of the brain, even less my sense that the hat is independent of me (a foundational intuition of physics) or that it has the potential to yield an infinity of other different appearances (the foundational intuition of the public world we humans live in). If the end-point of physics is the disappearance of appearance, it is impossible to see how there can be a physical explanation of the appearance of appearance.
So, the neural theory of consciousness is at odds with the very notion of matter that lies at the heart of the ‘orthodoxy’ – to use Dennett’s word – that underpins it. The ordinary concept of matter has its roots in the intuition that, while matter is ultimately revealed though sense perception, through intentionality, the material objects we perceive have an existence beyond the experiences we have of them. What objects are in themselves is disconnected from appearances. This becomes increasingly evident as the fundamental scientific idea of things being composed of ‘matter’ (or matter and energy) is elaborated. The objects that surround us are analysed as elementary particles that are remote from the phenomenal world experienced and lived in by conscious beings. As the scientific gaze goes beyond ordinary objects, perceived in the ordinary way, to their underlying material reality, so it progresses from things that have qualities to things that are characterised by numbers. It is not by accident that atoms are colourless, odourless etc and are defined by numbers that capture their size, speed and quantities. Experiences and experienced phenomena are replaced by numbers, patterns, and laws. There is a progressive disappearance of appearance.
Further empirical research within the current way of understanding the problem will not take us any closer to a neural explanation of consciousness. What is needed is a revolution in the way in which we approach the problem. This may require us to see that it is more than a problem. Or even, to use the standard term applied to phenomenal consciousness, ‘a hard problem’. It is a mystery.
Notes and References
62. Daniel C. Dennet Consciousness Explained (London: Penguin Books, 1991).
63. Galileo Galilei The Assayer published 1623
64. The idea that we get closer to the essence of something as we progressively abstract from it toward mathematics most certainly does not apply to consciousness. This does not stop Neuromaniacs such as Paul Churchland suggesting that sensations really boil down to spiking frequencies in different vector spaces of the brain. See Matter and Consciousness Revised edition (Bradford Book: MIT Press, Cambridge Mass 1988).
65. Iain McGilchrist The Master and His Emissary. The Divided Brain and the Making of the Western World (Yale University Press, 2009) p.19. Indeed, this ‘solution’ makes things worse for the neural theory of consciousness. Consider my consciousness of this rock in front of me. There is no such thing (within the rock) as what it is like to be that rock. And there is no such thing as what it is like to be my body qua organism. And there is no such thing as what it is like to be my brain understood as a material object. The McGilchrist version of the neural theory requires all three things, if I am to be aware of a rock. Most mysteriously, it requires that ‘what it is like to be a brain’ should be the revelation of what it is like to be a body and what a rock is like.
N.B. The above chapter is from Dr. Tallis's forthcoming book Aping Mankind: Neuromania, Darwinitis and the Misrepresentation of Humanity.