The unity of my mind is something that I can appreciate when I use it, but it is hard to isolate and analyse. Without it, I could not have checked that sentence or added this one to it, and yet, when I turn my mind inwards onto itself, the source of its unity remains elusive. Is it something additional to all my thoughts and feelings, wholly au-dessus de la mêlée? What are the vicissitudes through which this anima vagula is capable of maintaining its own identity? How separate is it from the rest of the natural world? That last question forces itself on us not only when we think about the possibility of surviving death but also when we make any ordinary choice in daily life. For whatever people end by thinking after they have studied philosophy and considered the arguments for determinism, there is no doubt that they begin with the conviction that they are genuine originators of their own actions, that when they choose to do them and do them, they could have chosen to refrain and refrained.
These questions are evidently deep and, if they are difficult, it ought at least to be clear in what direction I should look for their answers. Should I look to philosophy or to psychology? Should I turn my mind not onto itself but to its functions, in the hope that they will reveal how its unity is achieved? If I listen to philosophers, I shall probably start by reflecting on my memory, which gives me my sense of my own identity down to the present moment, but perhaps I ought also to include my intentions, because, when I extend this line in thought for a certain distance into the future, my own intended actions help to fix its orientation.
Or maybe the original source of my mental unity is the integration of my various sensory fields at any single moment. I see the fork on my left and the knife on my right and I know how to move my body in space in order to take in the food that I see in the centre, and, at an earlier stage, some other sense may have told me which way to go in order to get into the position to eat. Our philosophical tradition is a very theoretical one and it is easy for us to forget how much our own actions contribute to the picture of the world around us. We think of the world as our stage waiting there for our performance to begin. But the movements of infants exploring their own bodies and the space immediately surrounding them are actions, and, without having performed them ourselves, we would never have learnt to distinguish the actors from the stage. Our own bodies are only a special part of the natural world and their limits are discovered by experiment. This boundary provided Freud with a model when he drew the line between the Ego and the rest of the mind: the inner subject confronts the raw, unworked material of the Id in much the same way that the whole person confronts the external physical world.
But perhaps the integration of sensory fields is a function too close to the centre of the mind to give us a clear idea of the way in which our mental unity is achieved. Maybe we should look further out for the answers to our questions. The lens of the mind can hardly be turned onto itself and it may be easier to appreciate its unifying power if we look at its more distant achievements. There is a school of psychologists who suggest that the real person is not an elusive self au-dessus de la mêlée but simply the sum of the roles that he plays: we are like actors who never come off-stage, and no interview after the performance can reveal our true selves. If this view leaves us too hollow-centred, at least it stretches us to include more of the richness of our actual lives.
In the past, before psychology set itself up as a discipline distinct from philosophy, questions about the unity of the mind were even more baffling than they are today. Empiricists, like Locke, who were mainly concerned with the ways in which we are able to establish the identities of people through time – including our own – made the mistake of giving the function of memory too much work to do. It could hardly link mental episodes which lacked any other connection with one another, and so it could never provide the complete explanation of the unity of a mind. The point was well made by Kant, but the Idealists who followed him went further and placed the unifying power on a higher plane, where it became detached from the material needed in order to give it life.
Psychology has now achieved its independence from philosophy and what is hard for us today is not to avoid obliterating their separateness, but to bring them into any contact with one another. Jonathan Glover’s book is a rare attempt to carry out this difficult task. He writes to be understood by non-specialists who know enough about the different approaches to his subject to see that they must somehow meet on a single map, but do not see how to combine their various contributions. So on one side he reviews the philosophy of personal identity, and on the other he explains what can be learned about the unity of the mind from patients suffering from the loss of specific unifying functions.
The leading idea on the psychological side is that the best way to understand a very complex structure is not to speculate about its complete disintegration, but to observe the effect of the loss of each part separately. This is piecemeal, empirical work which was foreshadowed in some areas, and in a very general way, by the theories of philosophers. Kant, for example, explained the general need for integrating our sensory fields: but we now have empirical studies of specific breakdowns of integration. Locke described the general contribution of memory to a person’s sense of his own identity through time: but we now know something about the various kinds of brain-damage which lead to impairment or loss of this sense of oneself. Not all such losses, however, need be regarded as pathological. At the higher level of integration, where a person forms a view of himself, his actions and his motives, a certain amount of what is commonly called ‘self-deception’ is self-preservative – and anyway it might be excessive to deploy one’s whole self at every point.
It is not hard to appreciate the way in which the traditional philosophy of mind provided a framework for the detailed work that was to be done by psychology after it had established its independence. The unity of the mind was obviously indispensable and it was almost equally obvious that there was no way of accounting for it within an atomistic system like Hume’s. So though Kant’s treatment of the problem may strike contemporary psychologists as too a-priori, it is not somnambulistic. That is to say, he did not refuse to look at the terrain that he was covering, but, rather, already had the kind of familiarity with it that we all have, and, reflecting on it as a philosopher, was already able to draw an abstract map of it.
The relation between the psychology of personal identity and contemporary analytic philosophy is another matter. In one way it is easier to describe: we can simply say that philosophers analyse concepts used by psychologists and leave it at that. But this is a truism which leaves too much unexplained. The concept of the identity of a person has more than one aspect. There is, first, the line dividing me from not-me, a line which has been re-drawn in so many different ways by philosophers and psychologists. Then there is the need, already explained, for a unity of structure and organisation within this boundary, if what it encloses is going to count as a person at all. Finally, this boundary – or, at least, some of it – must be maintained through time if I am to have, and be aware of having, a certain identity. Of course, in order to remain the same particular person, I do not have to do anything except stay alive and allow the unifying thread to run on. When people say, ‘He is not the person that he used to be,’ they mean something different: they mean that he has changed in some important way and is no longer the same kind of person. In this sense of the word, my identity can be affected by my own actions and is obviously quite different from my identity as a particular person.
In the second part of his book Glover claims that I can do much to create my identity as the sort of person that I want to be. Given the profound difference between this ‘identity’ and my identity as a particular person, it is surprising that he makes the transition from the latter to the former without the philosophical comments and explanations that are needed in a book like his. If I hoped to have succeeded in a piece of ‘self-creation’ of this kind, I might be surprised to find that I had a double, but I would hardly be disappointed to find that I had not achieved a unique distinctiveness that had not been my goal. It would just be a rather unnerving case of finding myself in good company. The conceptual point is an extremely important one and this is not the only place where Glover treats the philosophical framework more cursorily than the material that has to be fitted into it.
The difference between particular identity and identity of kind has been used in some recent philosophical thought-experiments about personal identity. Suppose that my mental equipment down to the moment of my death is carried in duplicate in my brain – a complete version in each of my brain-hemispheres – and suppose that I am aware of this fact and bequeath my two hemispheres to the next two people to be so severely injured that they cannot survive without such transplants. So my beneficiaries are both going to ‘remember’ living my life. But will I survive in duplicate?
In his book Reasons and Persons, Derek Parfit argues that I will survive in duplicate, but without my identity, because the line of my particular identity could not possibly continue in both my beneficiaries simultaneously and there is no good reason to suppose that one of them carries it on rather than the other. This suggests some exciting conclusions. For example, it looks as if what really matters to a person is not the continuation of his particular identity but, rather, the continuation of the kind of person that he is and especially of his memories, provided that all this is carried over to another body in a suitable cutting from his body. It even looks as if selfishness may be founded on an exaggeration of the importance of particular identities.
Glover is sceptical about the more far-reaching conclusions drawn by Parfit from our supposed reactions to the fantastic predicament that he invents. He does not try to justify his scepticism, but if he is right, there must be something wrong with the argument. But what? Perhaps it depends on a mistaken view of the effect of the predicament on our instincts, or, to put it differently, on a misrepresentation of the logic of our emotions. A social animal not only preserves itself but also helps others of its kind. The first of these two instincts homes in on a particular body, the animal’s own, while the second homes in on similar, genetically-connected bodies. Even if it were true that in our case the targets are minds rather than bodies, it would not follow that, if self-preservation were deprived of its usual guide, particular identity, it would spread itself over the so-called ‘duplicate survivors’ of a person’s mind.
I am not just making the semantic point that when we say that a person survives, we mean that he survives as the same single person. This is true and worth noting if we feel like talking about ‘survival without identity’, but the more important point is that instincts atrophy in contexts in which they are no longer able to operate. So if the particular identities of people petered out in the circumstances imagined by Parfit, selfishness would vanish and the field would be left entirely free for impartial benevolence. It is true that this benevolence would be guided by shared characteristics which could have been used as indirect evidence of particular identities – if there had been any particular identities traversing the brain surgery to be discovered – but it does not follow that we would regard those characteristics as the substantial residue of the particular identities which had been discontinued. No doubt we feel inclined to regard them in that way when we describe our imagined predicament from the point of view set by the question ‘What would happen to our particular identities?’: but we do not have so to intellectualise the development of our emotional reactions. It would be more plausible to say that selfishness would atrophy, without any corresponding growth of unselfishness, and that we would find some of the targets of our impartial benevolence irresistibly attractive because of the instinct that impels like to help like.
In any case, whatever the outcome for selfishness in the situation imagined by Parfit, there is no reason why it should affect its standing in our lives as they are. It is a mistake to suppose that selfishness ought to be based on an unanalysable ego and that, therefore, when the basis of selfishness is analysed and dismantled in the imagined situation, it is shown to be ill-founded. Such thought-experiments leave its actual foundations, such as they are, untouched.
Can this kind of philosophical analysis ever produce a radical change in our view of ourselves, if not in this case, then in others? That is the deeper question raised by these two books. It is easy to see how a psychological discovery might produce this effect: if a certain chemical imbalance or damage to the brain is found to impair self-control, then it is humane to relax the ascription of responsibility to people who suffer from the impairment. But philosophical analysis merely reveals the structures of our concepts, their foundations and the contingencies that made it possible for them to establish themselves. However profound the understanding that such analysis yields, and however much it loosens the grip of our actual conceptual system on our minds, it is hard to see how it could produce by itself the kind of change in our view of ourselves that might have practical consequences.
The philosophical analysis of human agency may seem to transcend this limitation, but it does not really do so. If it has altered our view of our place in the world as human agents, it has never done so alone, but always aided by some factual hypothesis. This is very clear in cases of diminished responsibility and it ought to be equally clear in the limiting case in which the factual hypothesis is universal determinism. However, if we ask philosophers what our traditional concept of human agency is really like, we get a wide variety of answers. This is not just because they differ about the factors that diminish responsibility – those are perspicuous disputes about the precise limits of the justified imputability of actions and so of resentment, blame and punishment. Surprisingly, philosophers also disagree about the very centre of the concept of agency. Alan Donagan argues that to say, ‘He chose to do it,’ implies that, even if nothing else had been different, he could have chosen to refrain. On that analysis of the concept, it would atrophy if universal determinism came to be generally accepted. The obvious way to avoid exposing it to this risk is to moderate the implication that I have the complete liberty of indifference, and to argue that I have only the conditional power to have chosen otherwise – for example, I would have chosen otherwise if my reasoned preferences had been different. Glover moves cautiously towards this position, in spite of the promise of greater boldness that might be heard in his phrase ‘self-creation’.
If it is not clear exactly how much our traditional concept of human agency presupposes, it will not be easy to detect radical alterations to the concept. I do not mean changes in the precise limits of the justified imputability of actions – those are easily charted and, of course, very important. What is not so evident is the composition of the centre of this concept, which was formed before the development of modern science and then exposed to its discoveries and the inevitable speculations about their further implications. Is Donagan right in thinking that the concept was accurately delineated by Aristotle, and that its presupposition, worked out by Aquinas, is that we possess the liberty of complete indifference? Certainly, human agents must always have thought of their actions as, in some sense, a new beginning. But did they think this in the audacious sense that is given to it in this philosophical tradition? Did they detach their choices so completely from their psychological and physical antecedents? Or does this tradition read too much theory into the original concept? Perhaps the demand for the liberty of complete indifference only came later with the realisation that it might not be satisfiable. It is possible to walk in what feels like open country without asking oneself whether there is a distant perimeter wall – or even without having that concept.