No eternal truths, just divine advancements

There has been a lot of talk from physicists in recent years about unifying all the known particles and forces into "theories of everything", but these pale in comparison with the ambitions of the major philosophers of past centuries, such as Leibniz, Kant and Hegel, for whom everything truly meant everything. Their theorising was aimed at discovering the principles that underlay all human experience and knowledge, from history and ethics through natural sciences and on to the most abstract levels of mathematics and theology. Furthermore, few of our contemporary unifiers question received wisdom about the fundamentals, such as time and space or quantum theory. This stands in stark contrast to the ambitions of the major philosophers of the past, many of whom grounded their systematic thought in novel conceptions of space and time.

These days, few professional academics profess the ambitions of the great philosophers of the past, and it is not hard to understand why. Excessive ambition seems flaky to academic hiring committees; moreover, it is widely believed that the great systematic philosophers failed in their tasks to make true theories of everything, and that the wise course for philosophy is to limit its ambition to cleaning up conceptual and linguistic issues left by scientists.

One exception to this is Roberto Mangabeira Unger, whose book The Self Awakened shows him to be one of the few living philosophers whose thinking has the range of the great philosophers of the past.

His early work was in legal and social theory, areas in which he has a formidable reputation. A Brazilian who has been professor of law at Harvard University since the 1970s, Unger is regarded as the founder of an influential approach to legal theory called critical legal studies. He has written several books that aim to remake social and political theory on a basis that is progressive without being Marxist. Far from being one who lives only in his study, Unger has been very active in politics in Brazil and beyond as a candidate, activist and adviser, and he has recently been appointed Minister of Long-Term Planning in the Government of Brazil.

Unger has a restless and unruly mind, and is, I can report from several personal encounters, one of the most articulate and penetratingly original thinkers one is likely to meet. His ability to take a thought to a logical but completely surprising conclusion is on par with the greatest original mathematicians of our era such as Alain Connes, Roger Penrose and Edward Witten. His thinking and writing have always ranged beyond the boundaries of legal and social theory, to psychology, psychoanalysis and architecture. In this book, he takes on the task and direction of philosophy itself and draws out implications ranging from the theory and practice of politics, to psychology, to the most fundamental questions about space, time, cosmology, physics and mathematics.

The Self Awakened , Unger's 15th book, is highly accessible to a broadly educated reader. It is written in a vivid prose style that mixes precise lawyerly argument with poetic and metaphorical passages of astounding vividness. It is a polemic and a call to action, but what it challenges us to do most of all is to experiment with how we live and think. It is many years since I found myself as inspired and provoked by a book of non-fiction.

Unger aims at nothing less than to invent a new kind of politics, which is evolutionary in style but revolutionary in outcome. To do so, he offers a new interpretation of the pragmatist philosophers William James, Charles Sanders Peirce and John Dewey, reversing what Unger takes as an accommodation with contemporary political circumstances that has emasculated their meaning, leading to what he calls a philosophy of "singing in our chains".

From this starting point, he offers a novel conception of time, addressed simultaneously to time as studied by the physicist and time as conceived of by the historian, social theorist and psychologist. Indeed, one of the most challenging aspects of his thought is the way he takes contemporary science extremely seriously, without accepting the standard beliefs about the personal and social being reducible to the physical.

What Unger has to say about physics and cosmology is strikingly original but, at the same time, relevant to issues that dominate arguments over cosmology and physics that have received so much attention recently. His conceptions of time and mathematics are of interest because they offer a possible way out of the trap into which the crisis of string theory has led.

We physicists are just beginning to explore the possibility that the laws of nature may be changeable and different in different regions of space and time. This is difficult for us to accept, educated as we all have been with the idea that our job is the discovery of eternally true laws of nature. In this book, Unger jumps to the heart of this issue by offering a radically new conception of a law of nature that makes it not only understandable but necessary that laws of nature evolve in time.

Unger sees human society and human personalities as constructions in progress, ever incomplete, with futures radically open. One of his recurring images is of human beings as finite, limited by present circumstances and mortality but with virtually infinite potential for reimagination and reinvention of ourselves and our societies. He needs a novel theory of time because, for him, time - that is, the ubiquity of change - is the only aspect of reality that is not sooner or later subject to modification. This is opposed to the view, which he calls "the perennial philosophy", according to which change is an illusion that hides truths that are eternal and timeless. In Unger's cosmology, as in his social and psychological theories, the idea that anything is timeless contradicts the very definition of time, so that novelty and surprise are not only possible, they are essential. There are no such things as eternal laws, whether of physics or of society, and the difference between change and evolution according to law and the evolution of the laws themselves is only a matter of pace and scale.

In Unger's understanding of society, the distinction between that which is fixed and that which is modifiable is always negotiable. In his ideal society, something is always being challenged and renegotiated but, at any one time, enough is stable so that the fundamental rights and needs of ordinary people are respected. The distance between the things we do accepting the habits, laws and expectations of society and the things we do to change them is shrunk, enlarging the space for novelty and reinvention of ourselves and our societies. For Unger, this is necessary not only to achieve a more just society, without the violence of revolutions, but to make it possible to live a life more fully awake. Indeed, his conception of awakening our habitual selves by opening ourselves to surprise is reminiscent of mystics such as Georges Ivanovich Gurdjieff. But what is distinctive in Unger is how he gets there through an analysis of political theory, which makes manifest a connection between the shape of a better society, continually open to change and reinvention, and the personalities of those who will be able to build it, awake to normally hidden possibilities for their own actualisation.

This offers a conception of society that is progressive and hopeful without being prescriptive. Unger believes that the fundamental mistake that lay people and social theorists make is to take present circumstances constructed by previous generations as necessary aspects of life rather than as temporary solutions and compromises. Unger embraces the values and achievements of social democracy, but he also admires the innovative and open style of contemporary high-tech businesses, which he calls "experimental co-operation", with fluid roles for workers, managers and owners. In this way, his thought has something in common with the complexity theorists such as Per Bak and Stuart Kauffman because he shares with them the notion that an economy or society is too complex to give a fixed blueprint of the future. The role of theory is to make us aware of the possible next steps, which Kauffman calls the "adjacent possible" from which we may wisely choose.

This is a philosophy as ambitious as any being written now. It addresses and subsumes the postmodern critiques of why the great systematic philosophers failed, but then rejects relativism to move on to a new conceptualisation of a progressive agenda for thinkers and activists alike. In Unger's new world, we have to give up aspiring to the godlike view in which we can survey the truth, whether in mathematics or law, from a timeless and impersonal perspective.

What we get in its place is the possibility of a continual improvement of human beings and society towards the divine, by which Unger means towards a life in which one, as he puts it, dies but once in a lifetime.

Lee Smolin is a researcher at the Perimeter Institute for Theoretical Physics and an adjunct professor of physics at the University of Waterloo in Ontario, Canada.