Essay: God, neuroscience and human identity

Untangling personhood from consciousness, substance dualism and neurological reductionism

Competing understandings of personhood

We all have an internal sense that we are a unique individual, we have a “first person perspective”. But is this merely an illusion created by the neuronal machinery of the brain? What does it mean to be a person? Is it possible to exist as a living human being but not to qualify as being a person in some sense? On the other hand is it possible to be a person but not a living human being? Can a chimpanzee or an advanced artificial intelligence be thought of as a person? 

These questions may sound like pointless abstract speculations of the type that philosophers and theologians love to address. But in reality our understanding of what it means to be a person has profound consequences in the real world. Disagreements about what it means to be a person are at the root of many recent debates, in fields as diverse as medical ethics, law, psychology, social sciences, and even artificial intelligence and robotics.

My professional work as a neonatologist, a medical specialist in the intensive care of newborn infants, was based on a particular understanding of human personhood. Many of my patients were extremely premature infants, some born at the limits of viability at 22 or 23 weeks of gestation and weighing 500 grams or less. The ethical framework that I and my colleagues based our work on was to treat each baby as a unique and precious individual, to make decisions about intensive medical treatment which were in their own best interests and, wherever possible, to maximise their chances of healthy survival.

Personhood as related to self-awareness and autonomy

Some philosophers and ethicists have challenged the view that all newborn babies can be regarded as persons who are full members of the human community. For Peter Singer a “person” is a being who has a capacity for enjoyable experiences, for interacting with others, and for having preferences about continued life. It is clear that a newborn baby is not capable of interacting in any meaningful way and is unable to have preferences about their continued life. Singer puts Iike this; “When I think of myself as the person I now am, I realize that I did not come into existence until some time after birth.”  Hence a newborn baby is a human being but not a “person”.  

Philosopher John Harris has a definition which is similar although not identical. A person is “…a being who is capable of valuing their own existence…The value of my life is precisely the value I give to my own life”. Michael Tooley’s definition highlights the sense of having a narrative which extends over time. “A person is a being who is capable of understanding that they have a “’continuing self’”.

These definitions all point to the centrality of some form of self-awareness and it is obvious that a newborn baby will not qualify as a person, whatever the precise definition. This has profound implications for medical decisions about sustaining or ending life. As Peter Singer puts it, “Only a person can want to go on living, or have plans for the future, because only a person can understand the possibility of a future existence for herself or himself. This means that to end the lives of people against their will is different from ending the lives of beings who are not people…killing a person against his or her will is a much more serious wrong than killing a being who is not a person.” Singer goes further and argues that “….the decision to kill a newborn infant is no more – and no less – the prevention of the existence of an additional person, than is a decision not to reproduce.”

The same kind of thinking about personhood leads to the conclusion that individuals with severe learning disorders, brain injury or advanced dementia also cannot be regarded as persons. Personhood becomes defined by high-level cognitive functioning, an advanced level of integrated brain activity. In fact in order to be regarded as a person you must have a completely developed and normally functioning cerebral cortex.

Singer and others argue that those who meet the criteria of being “persons” have moral rights and privileges. They deserve to be protected from those who would injure or kill them. They should be allowed to exercise their own choices or autonomy as much as possible. But the same rights and privileges do not extend to “non-persons.”

Of course there are major problems with this kind of definition of personhood. Why should high-level cognitive functioning be the vital criterion that distinguishes those beings whose lives are precious and to be protected from those who are effectively disposable? Why should the functioning of the cortex, a layer of neurones millimetres in thickness, be the central and crucial moral discriminating feature between beings? It isn’t obvious that my cortical functioning should be the defining feature of my human worth and significance.

If my personhood depends from moment to moment on the precise functioning of my cerebral cortex then it becomes a remarkably fragile and contingent phenomenon. At this precise moment as I write these words, my cerebral cortex is functioning reasonably well (at least I hope so!) and I can be regarded as a person. But if, later today as I cycle back from work, I am involved in an unfortunate collision leading to severe head injury and cortical damage, then I will no longer be a person. Of course if, following rehabilitation, my cortical function recovers to a sufficient level, then I will become a person again.

Can something that seems so fundamental to my human identity and significance be so fragile and vulnerable to the contingencies of everyday life? Suppose I suffer severe brain injury but have the prospect of gradual recovery to normal cortical function. Am I a person in the intervening period? If someone killed me during the recovery period are they guilty of the serious crime of killing a person or the less serious crime of killing a non-person??! 

This is an extreme example of the questions and challenges which surround the sense we all have of being a ‘continuing self’, of having an identity that is preserved over time and space. Since all the molecules of my body and my brain are in a constant state of turnover with the environment, to what extent am I the same person as I was 10 years ago?

At the heart of the philosophical perspective put forward by Singer and Harris, as well as many other modern philosophers, is the idea that you earn the right to be called a person by what you can do, by demonstrating that your brain is functioning adequately, by thinking and choosing. This taps into the modern liberal emphasis on personal autonomy. To be a person is to be autonomous – self governing. The word is taken from autonomos – literally ‘I make my own laws’.

Substance dualism

It is interesting that liberal political philosophy is profoundly dualistic. ‘I’, the mysterious inner self, must be free to choose and to determine what happens to ‘me’, including what happens to my body. The conscious self is somehow disconnected from the body and is seen as its controller, governor and master. This conception of the human individual is rooted in the philosophical perspective of mind-body dualism pioneered by Descartes. It was re-emphasised by Immanuel Kant who stressed the significance and centrality of the autonomous thinking self.

The mind is conceived as a substance, a form of ‘stuff’, a thinking stuff that is different from the physical stuff of the body, and the two kinds of stuff or substances interact in a mysterious way within the brain. Although substance dualism was popular at the time of the Enlightenment it has become deeply unfashionable within the modern neuroscientific community. The dominant position of modern neuroscience is that there is no mysterious thinking ‘stuff’ connected to the brain. Most neuroscientists are resolutely materialist or physicalist in their understanding. The brain is a physical, material organ like all the other organs of the body and hence consciousness and self-awareness must have a physical origin within the activity of brain cells.

Physicalist understandings of conscious awareness

Some have argued that our sense of being a conscious, unitary, choosing self is merely an illusion created continuously by our brains because it has some survival advantage for us as a species. Francis Crick called this the ‘astonishing hypothesis’ – “You, your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will, are in fact no more than the behaviour of a vast assembly of nerve cells and their associated molecules.”  In the words of science journalist Matt Ridley, “There is no “me” inside my brain; there is only an ever-changing set of brain states, a distillation of history, emotion, instinct, experience, and the influence of other people – not to mention chance.”

According to this perspective our conscious awareness, our “first person perspective”, the internal sense of being a unitary, choosing self, is merely an epiphenomenon. It’s a kind of mental “froth” that eminates from our neuronal machinery but it has no causal significance for our bodily actions and behaviour. In a famous analogy it is like the steam that comes from the funnel of the locomotive. It is created by the mechanisms going on within the cylinders but it does not in itself influence the course of engine. Our actions are determined by the neuronal machinery, independent of our conscious thoughts and intentions.

There is a notable logical incoherence between the dominant liberal understanding of the autonomous choosing self that operates on the body, and the dominant physicalist understanding of the human brain, in which the sense of the unitary self is a pervasive illusion created by the working of the brain. As we saw earlier, within the influential thinking of Singer, Harris and Tooley, it is the autonomous choosing self whose preferences and choices must be respected. I, the self, can choose to do whatever I like with my own body. But this makes little rational sense within a physicalist understanding of brain function. There is no metaphysical distinction between the self and the body. The self is an emergent property of the body, derived and created by neuronal processes. Both ideas cannot be true at the same time. Either you believe in genuine choice, or you believe in physicalism – but you can’t believe in both – that would be incoherent. And yet this seems to be the position of many modern liberal thinkers!

(Photo by sharyn morrow)

Libet’s experiments and the problems of determinism

Some philosophers and neuroscientists have claimed support for a deterministic or ‘epiphenomenalist’ perspective from a series of experiments first pioneered by the neuroscientist Benjamin Libet in 1983. Libet asked volunteers to press a lever at a time of their choosing, whilst recording the subject’s EEG continuously as well as the precise time at which they noted their awareness of an intention to press the lever. Libet found that EEG changes (called the readiness potential) indicating neuronal preparedness to muscular action were detected significantly before the time at which the volunteer reported an awareness of an intention to press the lever.

These experimental results, which have been reproduced in a range of subsequent studies, have been interpreted to support a form of ‘hard determinism’. It is claimed that the actions of the subject in pressing the lever are determined by unconscious neuronal mechanisms and the subject’s belief that their actions were a result of voluntary choice was in reality due to retrospective rationalisation.

Experiments of this kind have been subject to a range of criticisms within the neuroscientific community and their relevance to philosophical questions of free will and determinism is questionable. The experimental design is highly artificial and it is clearly far-removed from normal motor behaviour. The experimental subject is primed to press the lever and is focussing intently on the single motor action that they have already determined in advance to perform. Motor function in human beings is not a good analogue of truly ‘voluntary’ behaviour. It is known to be largely mediated by subcortical processes which do not enter conscious awareness. For example the complex control mechanisms underlying walking or driving a car operate largely at an unconscious level. Hence the precise timing of the subcortical and cortical processes underlying voluntary movement compared with the timing of the conscious awareness of the intention to move a finger do not seem strictly relevant to broad questions of free will. Certainly it seems that Benjamin Libet himself did not interpret his experimental results as a demonstration of hard determinism.

An alternative philosophical perspective is that of non-reductive physicalism. Again the brain is seen as entirely physical and material in nature, and there is no other non-physical or mental “stuff”. However in this view it is possible for mental states to “emerge” from physical neuronal processes in a way that leads to new possibilities, including “top-down causation” in which mental states influence neuronal activity as well as the reverse. In other words mental states can have causal efficacy in the physical world. How it might be possible for mental states to provide top-down causation within a purely physicalist understanding of the brain remains highly contested and controversial.

Physicalist perspectives and artificial intelligence

Contemporary philosophical debates about human brain function have taken on a new importance because of the rapid development of computer systems capable of simulating human-like intelligence. If our brains are merely “computers made out of meat” as Marvin Minsky famously claimed, then there is no a priori reason why all aspects of human cognition and brain function cannot be accurately emulated within an advanced computer system. From a physicalist perspective there is nothing within the human brain that cannot in principle be reproduced within an artificial system. And we would expect such an artificial system ultimately to display the same emergent properties as intentionality, agency, rationality and forethought.

This kind of reasoning lies behind the concerns that have been expressed by a number of prominent scientists and technologists that advanced AI systems may represent a serious threat to the future of humanity. If all the evil intentions and the destructive actions of dictators and tyrants have emerged from the physical processes of human brains, why might they not similarly emerge from an advanced artificial mechanism? Why should we presume that the emergent intentions and rationalisations of advanced artificial intelligences will always be strictly benevolent towards the human race?

The human brain and the process of scientific research

Of course all attempts to use our brains to understand how our brains work may be doomed to failure. It has been said that “If the human brain was so simple that we could understand it, we would be so simple that we couldn’t understand anything……”  Nonetheless the very process of undertaking scientific research into the nature of the brain makes stringent and unavoidable demands upon our brain activity.

In order to do scientific research, including neuroscientific research, you have to believe that it is possible for a human being using a human brain to investigate and determine the scientific processes and regularities on which the brain is based. If our mental processes were merely determined by unconscious neuronal mechanisms it is hard to see how this should be possible.

As any experienced scientist will testify, planning and undertaking original research is an intensely creative activity. Using a previous example, Benjamin Libet and his colleagues created an original experimental paradigm. They chose (out of a myriad possibilities) a single motor action that was highly stereotyped and which could be timed to millisecond accuracy. They then created a novel method for the experimental human subject to time the onset of conscious awareness of an intention to act, using a rapidly sweeping pointer on a clock face. Yet, if hard determinism is correct, the sense the experimenters had of voluntarily choosing and creating their unique experimental paradigm was entirely illusory and the result of post hoc rationalisation. The design of the experiment was determined by unconscious neuronal mechanisms. Similarly their interpretation of their experimental results was in reality unconsciously determined.  

The practice of original scientific research depends on the belief that the researcher is genuinely free to create hypotheses and models, to design experiments, to assess evidence and to choose the most consistent interpretation of the data. But if you are committed to a physicalist understanding of the brain you have to ask whether these beliefs are logically coherent.

Darwinian orthodoxy teaches that the distinctive features of human brain function evolved because they provided a survival advantage on the African Savannah. Since human conscious awareness, and the ability for rational planning, forethought and creativity, require complex and nutritionally expensive processes, they must have provided a significant survival advantage. But this would strongly suggest that the microstructure of our brains and all our conscious mental processes are orientated towards providing a survival advantage rather than determining the truth about objective reality. Why should we trust the rationalisations that appear within our conscious awareness?

Of course the brain of the neuroscientist is not immune from these evolutionary processes and pressures. An entirely physicalist understanding of brain function leads one to conclude that all conscious beliefs, including the scientific conclusions of the neuroscientist, are likely to be unreliable. Our brains should be orientated towards survival not truth, and whenever there is a conflict between the two, survival should win. Yet the extraordinary success of modern science indicates that some human mental processes are in fact highly adapted to analysing and comprehending objective reality, even when such reality is extremely abstract, complex and counterintuitive.

Why is the universe comprehensible to human beings?

In 1916 Albert Einstein published his General Theory of Relativity, describing in precise mathematical detail how space and time were warped by the effects of gravity. His theory provided quantitative predictions on how a massive gravitational body would disturb space and time in its vicinity. On the basis of Einstein’s equations two phenomena were predicted, the “geodetic effect”, (warping of space-time vectors around a massive object), and “frame-dragging”(the amount a spinning object twists space and time with it as it rotates).

More than 80 years later, in 2004, NASA launched a satellite called Gravity Probe B to test the observed accuracy of predictions based on Einstein’s equations. The satellite carried the most mechanically precise gyroscopes ever engineered in order to measure the amount that space-time was warped by the presence of the spinning earth. It was calculated that the geodetic effect should cause the axes of the gyros to deviate by 0.0018 degrees per year whilst frame dragging should cause a separate perpendicular movement of 0.000011 degrees per year. This was described as equivalent to detecting the thickness of a sheet of paper held edge-on 100 miles away. The conclusion of NASA’s multi-million dollar experiment was that the observations fitted the warping of space-time predicted by Einstein’s equations to the limits of experimental accuracy. The abstract equations worked in the real world to the most mind-boggling level of accuracy.  

(Photo by NASA’s Marshall Space Flight Center)

But why should complex and abstract mathematical equations which emerged as a result of physical processes in the brain of a carbon-based life form describe with astonishing accuracy the counter-intuitive behaviour of the earth as it drags space and time around with it? As many philosophers have noted, there appears to be a strange connection, a homology, between the mind and thoughts of this pathetic and insignificant life form and the fundamental structures of the cosmos. As Einstein himself put it, “The eternal mystery of the world is its comprehensibility”.  

An alternative perspective – pansychism

Reflections like this have led some secular philosophers to conclude that mental states and consciousness are not merely a coincidental product of neo-Darwinian survival mechanisms. Our mental states appear to have a mysterious representational connection with the rest of the cosmos. For example the philosopher Thomas Nagel argues that the intelligibility of the world is no accident. He argues that minds are related to the natural order in two distinct ways. First, nature is such as to give rise to conscious beings with minds. Mind and conscious awareness emerge naturally and inevitably as a consequence of evolutionary mechanisms and increasing complexity. Second, nature is such as to be intelligible to conscious beings. The universe is more than merely physical – it is populated by minds of varying degrees of awareness and sophistication.

Nagel’s proposal is a form of “panpsychism” in which consciousness or mind is a universal feature of all physical objects, and the universe itself is orientated towards the emergence of advanced levels of conscious awareness and rationality. Nagel explicitly rejects a traditional form of Christian or theistic belief about a conscious and thinking creator, although he recognises the explanatory power of the theistic worldview. Instead he opts for a kind of natural teleology. He argues that the universe has the appearance of purpose, the fostering and emergence of mind, but it does not have a conscious creator or sustainer. Panpsychism is not a new idea, but for contemporary neuroscientists it is deeply unfashionable. Physicalists argue that it represents the worst kind of metaphysical speculation and that there is no empirical test that could decisively confirm or refute panpsychism.

Understanding personhood from the perspective of the Christian faith

In the history of philosophy, the very idea of a “person” has been strongly influenced by a Christian understanding of what it means to be a human being. The original Greek word for person (prosopon) meant literally “the face”, but in ancient Greek it also referred to the mask which actors used to represent the character they were playing in the theatre. In the world of Graeco-Roman thought what mattered about a human being was the face they showed to the world, the role they played in society. We have retained this meaning when we refer to someone’s “persona”. It is the public face they show to the world.

It is interesting that this is how the word is used in the Greek New Testament. At several points in Paul’s epistles God is described as one who shows no favouritism. The literal Greek says that he is not a respecter of persons, meaning that he is not influenced by our external and social role.

However in Hebrews 1:3 the Son is described as the exact representation of God’s nature and a different Greek word is used for the divine nature, the word hypostasis which means literally “what lies under”. The early Church Fathers, as they reflected on the nature of the Triune Godhead, fastened on this word hypostasis as a means of describing the three individual actors within the Godhead. God’s ultimate being, (what “lay under” his activity), was not merely substance, “God-stuff”, but was in the form of hypostases, persons giving themselves to one another in love.

Furthermore the Christian revelation makes the claim that human beings are created in God’s image. We are created to reflect the divine character and being. Because God’s nature is personal, then we too are created and embodied as persons.

Christian theism conceives of reality as consisting of more than just matter and energy. A purely materialist or physicalist description of reality will always be incomplete. There is another foundational category of reality and that is not “mind” or “consciousness” but the personal. As Martin Buber put it – reality does not only consist of “I – it” relationships – there are also “I-thou” relationships. Persons are not reducible to matter and energy and they are not limited to matter and energy. In technical terms personhood is a category of reality that is ontologically foundational – persons cannot be defined in terms of other more basic categories such as “substance” or “rationality”.

Persons are different from everything else in the cosmos

Persons are knowers – they perceive and understand things about reality. Einstein came to a profound understanding of the nature of space and time expressed in his theories of relativity. Persons are agents – they do things, they have intentions and volitions, they make things happen. Experimental scientists design and carry out experimental procedures with the intention of testing or falsifying hypotheses.

Persons are rational – they understand and use logical analysis to comprehend and change reality. Persons are communicative – they speak with the intention of being understood by other persons, and the expectation that their communication will be successful. Persons are creative – they are genuinely innovative and free. Persons are moral – they understand the concepts of good and evil and they are accountable for their moral choices. Persons are lovers – they enter into profound and committed relationships of union and communion with other persons. Union between persons emphasises the similarity between us. We are different persons but we are capable of profound union. Communion between persons emphasises the differences between us. The fascination of human relationships lies in the uniqueness of each person and therefore the uniqueness of each relationship.

None of these characteristics of human persons can be explained by or reduced to the nature of the physical universe, to the non-personal characteristics of matter and energy and physical laws. Persons are a different kind of reality.

In Christian thinking because our human identity is derived from the being and person of God himself, human personhood cannot be self-explanatory. Philosophical reflection and neuroscientific analysis can never fully determine what it means to be human. The structure of our humanity, and the values and purposes of our human lives, only make sense in the light of our creation in God’s image.

A theistic understanding of humanity underpins the scientific enterprise

A theistic understanding of humanity also provides a theoretical framework in which the scientific enterprise can be placed. Because we are God-like beings our thinking, our mental processes and subjective awareness, are somehow homologous, have a similar structure, to the mind of God himself, and hence to the fundamental structures of the cosmos. So the Christian faith provides a conceptual framework, an epistemology, in which the homology between the mind of the human scientist and the structures of the universe makes sense. As the astronomer Johannes Kepler put it, “I am thinking God’s thoughts after him..”  It is not surprising that many historians of science trace a causal link between theistic thinking and the rise of modern science in the 17th and 18th centuries.

Personhood in the light of Trinitarian thinking

Just as the three persons of the Trinity are individually unique, yet give themselves to each other continually in love, so each human person is unique, yet made for relationship with others. “Personhood” is not something we can have in isolation – in Christian thinking it is a relational concept. Persons are constituted by their relations – their very being is derived from the movement of communion and love, from the freedom to give oneself to the other.

Descartes’ famous statement, “cogito ergo sum, I think therefore I am”, places individual conscious awareness as the bed-rock of existence. When everything else can be doubted, the final place for certainty is my own self-awareness. But this way of thinking leads inexorably to a profound individualism, which is one of the recurring features of modern liberal thinking.

By contrast we might suggest an alternative Christian version, “amor ergo sum, I am being loved therefore I am”. My being comes not from my rational abilities or self awareness but from the fact that I am known and loved by others. In the words of the Christian philosopher Joseph Pieper, “Love is a way of saying to a person, ‘It’s good that you exist, it’s good that you are in the world’”

In my professional work as a neonatologist these Christian reflections led to a new recognition of the innate personhood of the critically ill preterm baby in my care. Instead of focussing on their limited functional abilities and reducing them to the status of a “non-person”, or merely a “potential person”, Christian thinking calls us called to recognise each baby as a mysterious other, a “thou” not an “it”, and a person to whom we as professionals owe a duty of care and protection. It is notable that contemporary understandings and practices of medicine and law in neonatology still reflect a Christian understanding of personhood from the moment of birth, rather than the preference utilitarianism of Singer and colleagues.

Conclusion – the unity of the human person

To conclude; it seems to me that both Christian thinking and contemporary neuroscience resist the substance dualism of Descartes, and emphasise the unity of our being. Human beings are not made out of two different substances. But Christian thinking cannot accept a physicalism that fails to give ontological respect to the immaterial aspects of being human. From a historic Christian perspective the human being is seen as a profound unity, a unity that has both a physical, material aspect and an immaterial, personal aspect.

How these two different aspects – the material and the immaterial – interrelate and integrate within the unity of the human person is deeply mysterious. Perhaps there is a parallel in the traditional theology of Christology. The Council of Chalcedon in AD 451 wrestled with competing understandings of the being of Christ. The Church Fathers were at pains to preserve the unity of the personhood of Christ despite the orthodox understanding that Christ was both human and divine. They eventually agreed on the formula that “Christ is one person (hypostasis) who is one being (homoousion) with the Father, and one being (homoousion) with us – one person in two natures.”  In the orthodox formulation Christ is both fully human and fully divine.  

Of course it is unwise to press the comparison between our own human nature as created, limited and embodied beings, and that of Christ himself. But with due caution it may be possible to speculate that the unity of the human being – one person with both material and immaterial aspects – parallels in some mysterious way the profound unity of the Second Person of the Trinity. This ‘Chalcedonian ontology’ is neither monist or dualist, it is neither physicalist or idealist. The profound mystery of the human person transcends these distinctions. Each one of us is an integrated unity constituted by our relations with other persons – at the same time fully material and fully immaterial.

Further reading:

Matters of Life & Death, John Wyatt (InterVarsity Press)

Being as Communion, John Zizoulas (St Vladimir’s Seminary Press)

Mind and Cosmos, Thomas Nagel (OUP)

Neuroscience, Psychology and Religion, Malcolm Jeeves & Warren Brown (Templeton Science and Religion)

Leave a Reply

Most read posts
What can we learn from how the early church lived out their faith during their own pandemics?
Navigating the transitions of later life
How are young people different to those who came before, and what can we learn from them?
Living faithfully as we approach retirement, dependence, dementia and death
Investing in the next generation - Lessons from John Stott and others
Recent posts
How can the church engage in conversation about people with autism with care and compassion?
Can AI friends stop us feeling alone?
Science and religion in the 21st century
A bad law but also an inevitable one?
Identifying and confronting abuse, while caring for victims, has never been more important