This way madness lies

Jean Lott, a dinner lady at a school in Southall, hanged herself one morning in March 1988. She had spent the last few months looking after her severely depressed son, Tim. Tim was thought to be suicidal. She was not. To the end, she had been coping well. On her last morning she had "done her jobs", tidying her home and telephoning the school to say that she would not be in. Yet in her note to her husband, Jack, she said: "I hate Southall, I can see only decay, I feel alone."

How should we understand Jean Lott's suicide? A broken brain? Or a broken life? A loss of brain amines? Or a loss of life's meaning?

Derek Bolton and Jonathan Hill bring a strikingly novel developmental approach to these formal but all-too-human questions. There are no people in their book. It is a lively mix of Wittgenstein and postempiricism, cognitive psychology and information theory. Jean Lott's suicide is described by her son Tim Lott in The Scent of Dry Roses (1996). Yet Bolton and Hill face precisely the same dilemma as Tim Lott - how to square meaning (mind) with madness (brain).

This is a two-millennium dilemma: how to square mind with brain, free will with determinism, or, in modern philosophy of mind, meaning with mechanism, reasons with causes. Like many, Bolton and Hill argue that the mind/brain dilemma is false, that there is no gap between mind and brain, between reasons and causes. But they bring a new twist to this by riding the wave of interest among philosophers in disordered minds. They are well placed for it. Bolton is a former philosophy lecturer at Kings College London, and now head of clinical psychology at the Institute of Psychiatry. Hill is professor of psychiatry at Liverpool University.

The key to closing the gap between mind and brain, they suggest, is to focus on an important feature shared by all mental phenomena, namely that they are intentional. This term is perversely misleading. It means that, like intentions (used in its everyday sense), all mental phenomena are about something else I intend to go out (my intention is about going out); similarly, I wish to go out, or, I remember going out, and so on.

Now, if all mental phenomena are about things, then they are, in some sense or degree, representational - they represent the things they are about. But if they represent things, then they carry information; and if they carry information, then, like a computer program, they can be causally efficacious. Ergo, mental phenomena, including reasons, are causes, mind is mechanism.

There are differences between this "intentional causality", as Bolton and Hill call it, the causality characteristic of mind, and the causality characteristic of, say, billiard balls knocking each other about. But intentional causality is enough to explain how reasons can move us. It explains how disordered reasons (broken minds as against, merely, broken brains) can move us in disorderly ways. For it leads to a whole series of scenarios in which the information content of different representations may be, to a greater or lesser extent, in conflict. Bolton and Hill illustrate the possibilities here in a fascinating concluding chapter covering schizophrenia, obsession, anxiety and post-traumatic stress disorder. This is not psychoanalysis by another name. For the models their theory generates are not located in a scientifically inaccessible unconscious, but, plain for all to see, in the conscious world of cognitive science.

Science? But hang on a minute. Isn't something fishy here? We started off trying to square reasons and causes. We have ended up assimilating reasons to causes.

This is a tempting assimilation. Science is such a success that everyone wants "in". Bolton and Hill certainly want "in". If meanings and reasons can be made causally efficacious, they say, this will bring psychology firmly in the scientific fold. And why not? Science is progressive. It explains things. It relieves suffering. It cures illnesses. With new techniques of brain imaging - allowing us to "see" mental processes as they happen - perhaps it really can cure mental illnesses. Peter Fenwick, a neuropsychiatrist at the Institute of Psychiatry in London, already has a brain imaging picture of guilt. In artificial intelligence, too, things are moving. Work on cyber emotions, simulating what Margaret Boden, professor of philosophy and psychology at Sussex University, has called the "warm-blooded" mental functions of affect, emotion, desire and volition, is producing increasingly realistic models of madness.

Well and good. Yet there is a world of difference between using science to explain human behaviour, and believing that everything we need to understand about people can be understood in this way.

There is a certain triumphalism around in science today. Colin Blakemore, Richard Dawkins, Stephen Hawking (familiar names all) tell us that we should forget the "why?" questions, that we should ask only "how?".

In psychiatry, too, the biological paradigm is king. But what could be the scientific justification for a belief in the completeness of science? To claim that science is everything, is to turn away from all that is best about science itself - its modesty, its focus on well-defined problems, its openness to falsification, its self-imposed discipline of objectivity.

This triumphalism is not in Bolton and Hill's book. It is careful, detailed, and balanced. Difficult areas are presented lucidly, even wittily (I laughed out loud at their dig at certain forms of therapy as "backward trauma hunting"). It could stand alone as a tremendous introduction to many of the liveliest debates in philosophy of mind. But the book's persuasiveness makes the dangers of assimilation the greater. There is everything of science here; but no people. There are minds and mechanisms, information processing systems, causally efficacious representational states; but there are no reasons, no meanings. For these I had to go to Tim Lott's mother. Biological psychiatry, at its most crass would have offered Jean Lott a pill. Bolton and Hill offer her, in principle (though they certainly do not say this) reprogramming. Both could (perhaps) have saved her life. But if this is the future of meaning, could it have given Jean Lott a meaningful future?

Bill Fulford is professor of philosophy and mental health, University of Warwick.