What makes us human? The way we think is surely part of the answer. Among our thinking skills, self-awareness is a promising candidate for the cognitive capacity that sets us apart from the other animals on earth. The distinction is not absolute – evolutionary differences seldom are. We know that chimpanzees can recognise themselves in mirrors, and to that extent are self-conscious. But it is likely that we and only we have a really well-developed understanding of ourselves as subjects of experience — as animals with minds. We put this to work when we ponder our own and others' thoughts and feelings. Our self-awareness feeds our addiction to "mental time travel", by which we project ourselves into the past when we reminisce, and into the future in imaginative thought. These capacities, for "theory of mind" and mental time travel, together with our closely related talent for language, have been identified by many contemporary thinkers — in psychology, anthropology and elsewhere — as the intellectual hallmarks of adult humankind. But if we want to understand how we experience the world, listing capacities does only half the job, as it says little about the content of our self-understanding. This has changed radically in the course of human history. We believe that this content is in the midst of a revolution which originates in science but is destined for a much wider cultural expression.
Of all the questions we can ask about ourselves and our world, among the most fundamental are those which concern our understanding of what matter is, what mind is, and their relation with one another. Two kinds of answer to these questions have been given, roughly successively. The first has been described by Charles Taylor as envisaging an "enchanted universe" in which matter is "porous" to mind, and mind to matter. This view is animistic — it takes the natural world to be richly populated with various kinds of mind — and anthropomorphic — it explains the workings of nature in human terms. It draws no sharp distinction between the "mental" and "physical" and assumes that the human meanings we find in the universe belong precisely there. There are "tongues in trees, books in the running brooks/Sermons in stones, and good in everything". Such a view lingers in some of our more ancient artefacts, practices and beliefs, especially those associated with art and religion, in the light cast by the scientific revolution, and have become the object of both fascination and perplexity.
The porous view has been replaced by a very different conception of nature. From René Descartes and Isaac Newton to David Hume and Immanuel Kant, the material world has come to be seen as mindless, and the mind as set against it. Enchantment gives way to disenchantment, the porous interconnections between mind and matter are replaced by a sharp boundary that defines the "buffered self". The movements of the planets, the processes of life, indeed the workings of our own bodies are reconceived in terms of wonderfully intricate machinery. As the medical historian Charles Singer wrote: "The course of physiological advance may be described briefly as the expulsion of the mental element from process after process associated with vital activity." The mind became an anomaly in the material world: the 17th-century chemist Robert Boyle described this ethereal being as "a kind of imprisoned angel". Inheriting this tradition, the great neurophysiologist Sir Charles Sherrington noted — with considerable frustration — "to man's understanding the world remain[s] obstinately double".
This dualistic tradition was bound, sooner or later, to confront its own incoherence. Charles Singer's words anticipate this moment-the process of "expulsion" he described had, eventually, to stop, as it became ever clearer that one set of vital processes, those occurring in the brain, were precisely the source of the "mental element" in our lives. This knowledge, was to some degree, ancient — Hippocrates had written 500 years before the Christian era that "from the brain and from the brain only arise all our pleasures, joys, laughters and jests, as well as our sorrows, pains, griefs and tears". In the 17th century, Thomas Willis, the royalist physician, father of neurology and founder member of the Royal Society, had "addicted [himself] to the opening of heads" precisely to "unlock the secret places of man's mind". Paul Broca, the 19th century Parisian neurologist and anthropologist, wrote that "the great regions of the mind correspond to the great regions of the brain". These thinkers recognised that mind is the intimate, not the antithesis, of matter.
For Hippocrates, Willis and Broca, this knowledge was hard won, provocative and, to many, obscure. Times have changed. Over the past 50 years the truly astonishing achievements of "neuroimaging" – the achievements, to a great extent, of physicists and engineers – have revealed the workings of the living brain in vivid detail. It is very likely indeed that we have much more to learn about the brain than we have so far discovered, but who would have guessed, in 1970, that within 50 years we would be able to glimpse the neural activity that gives rise to visual imagery, romantic love, the shivers down the spine aroused by music, the psychedelic dissolution of the self described by Aldous Huxley, the misery of depression, the recollection of our past? The thought that discoverable features of brain activity would track the contours of our experience was at best an article of faith in neuroscience when we were students in the 1970s: it has been richly vindicated.
We have also learned that the brain is a more congenial home for the self than it seemed to be back then. The familiar analogy between brain and computer, and the emphasis in much research on the brain's response to stimulation, conceal the crucial truths that the brain is autonomously active and ceaselessly creative. Stimulation of the brain has only a marginal effect on its level of activity, which is mostly internally driven, for example by the cycle of waking and sleep. Both when we wake and when we dream, a highly organised yet highly dynamic set of networks within the brain constantly produces our world of experience, predicting our future, and taking account of our (not infrequent) errors of prediction. As one would hope, given the multiple facets of our experience, the brain revealed by contemporary neuroscience is Janus-faced, looking both within and without, at times introspective, at times directed outwards to the physical, social and cultural worlds we inhabit, to which it is fully attuned.
Recent research, and the thinking that it has inspired, does not point to any simple reductive identity of mind and brain. An influential, and representative, theory of consciousness, Giulio Tononi's theory of "integrated information", suggests that all of nature has a – sometimes – hidden potential for mentality. The Canadian philosopher Evan Thompson has underlined the way in which the precursors of minds like ours can be glimpsed in even the simplest of organisms. Other contemporary philosophers, including Edinburgh's Andy Clark, have emphasised that human minds are sustained by culture and community. The role of action and the body in forming and mediating consciousness has been a key theme in the work of the American neurologist Antonio Damasio, the Parisian psychologist Kevin O'Regan, the Berkeley philosopher Alva Noë and the Brighton-based psychiatrist Hugo Critchley. In the work of these thinkers, mind is understood to be "extended, embodied and embedded" – extended in its interactions with space and time, embodied through its dialogue with both the body and the brain, and embedded in human culture and society.
We believe that the combined result of all these developments will be a new world view, replacing both the "porous" and the "buffered" understanding of ourselves. The earlier undifferentiated view of mind and matter, and its successor, the radically differentiated Cartesian view, will gradually give way to a more fully integrated understanding, which acknowledges both our ineradicable subjectivity and our inextricable, yet often invisible, involvement with matter. We will come to recognise that the line between mind and matter, like the line of demarcation between psychiatry and medicine, has been drawn in the wrong way and in the wrong place. We will come to understand ourselves as free within rather than from our material existence.
Brain imaging remains a crude tool with which to probe the astonishing scale and subtlety of the human brain, but over the past 30 years it has thrown our continuous dependence on the matter of our minds into sharp relief. The cultural impact of these images is growing, just as the precarious glimpses of Jupiter's transiting moons through Galileo's clunky telescope were far more revolutionary than all the fine diagrams or subtle computations of Copernicus and Kepler during the previous "scientific" shift in our self-understanding. Where will the new vision take us?
It is too soon to tell. One thing is sure, however, that it calls into question our dualist inheritance, and prompts us to consider the ways in which mind and matter form an integrated system in us, just as the fundamental physics of matter calls into question the distinction between the mind and the world around us. We have to wonder, then, what kind of cultural collapse, evolution or accommodation will take place in the face of the new science, especially as its technologies begin to redefine the parameters of our social, economic and medical lives. Will dualists in years to come gather like smokers on the margins of our social spaces, indulging together their passion for illusion? If so, what will prompt change: human telepathic communication through enhancement of neural activity? Telekinetic control of our surroundings? Conscious computers? And what kind of change will it be: how will "integralists" think — culturally, socially and philosophically? How will we make sense of ourselves and others when we understand that we are materiality so complex, and so alive, that it becomes self-aware? We are optimistic that the new vision of human nature will help us to make better sense of at least three important areas of concern.
First, it should help us to fathom our individuality and subjectivity. Our sense of our own uniqueness, of the key fact about my life that "I" and no one else has this particular perspective on this particular time and place, can appear antithetical to the "view from nowhere" to which science aspires. Alain Badiou has rightly lamented the loss of what he calls "the uncountable infinity constituted by a single human life" in this age of anonymity and digitisation. Yet biology and neuroscience have much to say about this irreducible particularity of the person, which is the source of so much that we value. Individuality and interiority are notable features of organisms generally, and the extraordinary complexity of our brain, with its thousand million million modifiable connections, is surely relevant to the subtleties of human variation.
Second, we believe that the new paradigm will help us to understand how religions work, and how they can go wrong. These ancient traditions straddle the globe and deeply shape our contemporary world. Under a dualist view, it was difficult to make sense of religious practices and embedded beliefs since these are the product of earlier ages and integrated cosmologies which assumed a "porous" relationship between mind and body, self and world. Religions have so baffled and fascinated us because they were born "under different skies". Religions, like magic perhaps, have such a strong hold on our imaginations partly because they presuppose a participatory relationship between mind and world that dualistic science denies. The new scientific view of the human, which respects consciousness as an integral "feature of the world", is in fact surprisingly close to the metaphysical realism and theistic cosmologies of medieval Abrahamic religions, mutatis mutandis. Late medieval thinkers, such as Duns Scotus, anticipated many of the insights of the "embodied cognition" of our own age.
Finally, the integrated view simply offers a more accurate description of what is going on in us as self-aware human beings than does the dualist one. Dualist philosophies were the natural and creative response to the rise of reductionist materialism, but they will always be limited in their critical power since dualism is based on incomplete science. The integrated view offers a more grounded account of what we are like as both body and mind, and so should help to illuminate our individual and, importantly, our social lives. The growing neuroscientific interest in the "second person", in how I and Thou (to use Martin Buber's terminology) communicate and interrelate, may offer real help in dealing with human conflict. How are community or family mediators, for instance, sometimes able to effect such rapid and lasting change in the face of deep-seated hostilities? Professional mediators "know how it is done" — they have an intuitive, implicit grasp of what to do. An integrated understanding of how body and mind combine in our social existence may offer a theoretical explanation of how this happens, which we can "port" from one context to another. This opens up the intriguing possibility that we can learn from our own best practice in one area and then recreate it in a wholly different context, such as the present encounter between China and the West. Indeed, this approach is showing promise. Chinese identity presupposes a particular way of managing social difference, based on harmony and assimilation, while Western identity has a contrasting tradition, based on confrontation followed by reconciliation and peace-building. Each identity manages social difference differently. A more broadly based understanding, working with the neurobiology of primary human social cognition, may allow us helpfully to reconcile these contrasting approaches in a new species-wide account of how we can best manage and positively adjust to difference.
Will the conception of human nature that will succeed the porous and the buffered views contribute to human wellbeing? We hope and believe so. After a period of "neuromania", a "neurophobic" scepticism about the relevance of neuroscience to understanding human nature is becoming fashionable. We believe this is misplaced. There is no need to defend mind against matter in this way. The absorbing challenge is to understand their manifest and mysterious integration, and then to apply this new self-understanding. We believe that it will help us to humanise our rapidly globalising world.