Books: The heart between the mind and brain

There is in the modern world a paradox about how to understand what it means to be human. On the one hand, science has taught us to conceive of Nature in largely mechanistic terms, a process that has driven out magic and mysticism and "disenchanted" the natural world. On the other hand, we regard humans as beings possessing consciousness and agency, qualities difficult to express in physical terms. We view human bodies as machines; but we express our humanity precisely to the extent that we do not treat fellow humans as if they were machines.

The problem of how to relate objective knowledge to subjective feelings has been a central theme for science, philosophy and ethics over the past half millennium. Descartes' solution - the separation of mind and matter into radically different realms - still shapes much of the way we think about the world and our place within it. For most scientists, however, Descartes' argument seems a throwback to mysticism. There are few more loaded scientific insults than to dismiss someone as a "dualist".

Those who reject dualism have generally taken one of two approaches. Some, like Daniel Dennett, dismiss consciousness as an illusion. Others, such as Jacques Derrida, claim that physical reality is itself a subjective creation. The philosopher John Searle rejects both these views, one as crass materialism, the other as akin to mysticism. Searle places himself firmly in the Enlightenment tradition which "assumes that the universe is completely understandable and that we are capable of a systematic understanding of its nature". But, he insists, understanding objective reality requires an understanding of the reality of subjective thoughts and feelings.

Mind, Language and Society is both an introduction to Searle's philosophy and a summation of a lifetime's work. Few philosophers write with the verve of Searle, and, even for those familiar with his work, Mind, Language and Society provides an exciting ride through some of the more intractable problems of contemporary philosophy. But inevitably, in a book that crams four decades of thinking into 160 pages, the arguments are highly compressed, and one often wishes for a more thoroughly argued account.

Searle was going to subtitle the book How it all hangs together, which would have been a perfect description of his project. What he sets out to show is how the social and natural worlds mesh together and how nature, mind, language and society can all be explained within a general philosophical theory. Searle begins with a defence of the idea that the universe exists independently of our minds and that we can comprehend its nature. He finishes with a discussion of how we can create our social world and yet still regard it as an objective reality. But the heart of the book lies in between when he discusses the mind-brain problem (how the seemingly immaterial mind can be created from the material brain) and the question of intentionality (how subjective intentions can create changes in the objective world).

How is it possible, Searle asks, that a world consisting entirely of material particles in fields of force can contain systems that are conscious? The only way to make sense of this, he suggests, is by abandoning traditional definitions of "mental" and "physical", of "mind" and "consciousness" and of "causation". "The way to defeat dualism", he writes, "is simply to refuse to accept the system of categories that makes consciousness out as something nonbiological".

Searle argues that consciousness is caused by brain processes but is itself a "high-level" feature of the brain. Simply by viewing consciousness in this fashion, he claims, it is possible to avoid the pitfalls of both crass materialism and idealist mysticism. As for intentionality, Searle suggests that we must abandon "billiard ball" notion of causation - the idea that causation requires physical contact between two objects. In reality causation is a lot more complex. We debate the causes of war in Kosovo, of poverty in Africa, of the Spice Girls' success, of Liverpool's failure to win the Premiership. We understand, in other words, that causation is not simply physical, but can be mental, social, political or economic. By viewing causation in a more complex fashion, Searle argues, by accepting that consciousness can cause things to happen, we can make sense of intentionality.

I am deeply sympathetic to Searle's project of establishing a materialist account of mind that does not eliminate the subjective aspects of being. However, many of his arguments leave me unconvinced. His solution to the mind-brain problem is simply to turn a description into an explanation. We know that consciousness is caused by neurophysiological processes but cannot be seen as simply neurophysiological. But stating this, as Searle does, is not the same as explaining it, which he fails to do.

In many ways Searle's argument seems not to go far enough. His starting point is that our subjective feelings - desires, intentions, beliefs - are located inside our heads. But are they? The neurophysiological processes that give rise to subjective consciousness certainly reside in our individual brains. But our subjective feelings depend, paradoxically, on the fact that we are social beings, that we live in a community of others similar to ourselves. In some sense, then, our subjective feelings lie not simply in our heads, but outside them too, in the relations with our fellow humans. To understand mind, therefore, requires a much greater rejection of traditional concepts and categories than even Searle allows for.

All this suggests that truly to understand mind, language and society we need to develop a methodology that we do not yet possess. In the meantime John Searle remains both one of the best guides to the debate as it exists now, and one of the most pugnacious defenders of the Enlightenment tradition.