Are the mind and the body separate entities, or one and the same thing? If they are separate, how do they relate? If they are one 'substance', is this substance mental or purely physical in nature? The 'mind-body problem', the difficulty of understanding how mind and body (or brain) relate, has fascinated philosophers for centuries and has profound implications for how we think about and treat other human beings. This File introduces some key aspects of the debate.

Stories of out of body experiences, beliefs in life after death, or diseases affecting the brain all raise questions about whether our minds and our bodies are separate entities that have the ability to exist independently.

Out of body experiences can occur under the influence of drugs, as part of religious experience, or close to death. During an out of body experience the person has the impression that their mind (or soul) is somehow leaving their physical body. Some people believe that these experiences are just 'a trick of the mind', but others see them as evidence that the body and mind really can exist independently.

Belief in life after death is common in many religious and cultural traditions. Some people, particularly in the Western world, believe that death is the end of existence. Others believe that we continue to live after our body has died, either as dismembered spirits, or to be 're-clothed' with a new body, either reincarnated in this world or resurrected into a new world.

Schizophrenia and Alzheimer's disease are two examples of diseases affecting the mind where only the 'shell' of the original person appears to be left. Relatives and carers are left caring for those who appear utterly different from the people they once knew and loved. What actually happens when the mind goes?

Mind and matter

The 'mind-body problem' centres on whether the mind and the body are separate things or one and the same. There are two main competing theories, dualism and monism.

Dualism

The ancient Greek philosopher Plato was one of the first dualists. He believed that the soul was distinct from the body and could maintain a separate existence from it. He also believed in reincarnation. Dualists differ on how they think the mind and body relate and interact.

Some believe in parallelism, in which the mental and physical realms do not influence each other. Most parallelists believe that God has made us so that our mental and physical elements are synchronised and appear to interact. For example, placing your hand on a hot stove does not cause pain, but is rather an occasion for God to cause the mental state of pain. In this case, mind/body causal interactions become the work of God.

Most dualists, however, believe that mind and body do interact. René Descartes popularised this view, which is sometimes called Cartesian interactionist dualism. Descartes believed that mind and matter were separate substances, but that mind could cause matter to act (e.g. I can choose to make a fist), and that matter could cause mind to have sensations (e.g. I feel pain after striking my thumb with a hammer). Descartes also believed that mind and matter could exist independently. But how can mind and matter interact when they are different substances? Descartes' view, like many parallelists, was that God was responsible for these interactions.

Some modern dualists say that the problem is with our understanding of reality. For example, in modern physics, light behaves in some circumstances like a wave of energy, and at other times like a particle. But light, in essence, is neither a wave nor a particle but something else. In the same way our understanding of matter and mind itself may be inaccurate. If we understood what mind and matter really were, they argue, we would also see how it is possible for them to interact without having to bring God into the equation.

Monism

Monism, the belief that mind and matter are essentially one substance, is often associated with Aristotle. Monists can be divided into idealists, who believe that only mind and mental processes exist, and materialists, who believe that only matter exists. George Berkeley, an idealist, postulated that the physical realm is just a collection of ideas, that exist either in our minds, or in other minds, or in the mind of God. Spinoza believed that the mental and physical were simply two modes of a more basic substance, which he called God or Nature.

Many modern philosophers and scientists are materialists, believing that everything is material or physical. They use the terms material and physical interchangeably, although strictly speaking, physicalists would say that energy exists as well as matter. Materialism has become much more popular in recent years. Now many people in the Western world believe not only that human beings are simply very complex machines, but that all our mental processes can be explained purely in terms of physics and biochemistry. There are three main reasons for this.

First, scientific research has revealed much more of the complex biochemical changes that occur in the brain's neural pathways when we think, act or sense what is going on in our bodies or in the world around us. Authors such as Oxford professor Susan Greenfield have popularised many of the recent exciting advances in our understanding of brain function.

Secondly, the new complex computers that mimic some of the functions of the human brain (in many cases more quickly) have led many to ask whether our brains are simply complex computers.

Thirdly, increasing numbers of people accept an atheistic world view. They believe that everything, including the origin of life and the universe itself, can be explained in terms of random chance and natural processes. Such people look to physical matter to provide all their answers. They deny the existence of anything 'supernatural'.

Glossary

• Mind-Body Problem - the problem of describing the relationship between the mind and the body (or brain)
• Dualism - the view that mind and body exist as separate entities, which may or may not interact
• Monism - the view that all reality is of one kind, either mental or material
• Materialism - the view that only material objects exist
• Physicalism - the view that only matter and energy exist Idealism - the view that only minds and mental events exist

Questioning materialism

Of course these various views of how mind and body relate cannot all be equally correct. In fact, some are mutually exclusive. So which view best explains the diversity of 'physical' and 'mental' phenomena that we experience in the world about us? The answer has eluded some of the greatest minds in history, but we can start by assessing the predominant world view in Western society, before bringing a Christian perspective to bear on the issue.

Materialism has been criticised because it fails to explain everything and it has unfortunate implications for the way we treat human beings.

Explanatory power

Materialists have difficulty explaining how their theory can account for such psychological phenomena as desires, intentions, sensory experiences, thoughts and beliefs.

Most of us believe that we have freedom to make choices, and that the 'I' that chooses somehow stands outside the chain of cause and effect. If not, our choices are determined as Skinner and Ryle, two influential twentieth century writers, believed. But, if we have no option when faced with a choice, surely it was never a choice in the first place?

Most of us naturally believe that there is actually an 'I' that feels and is conscious - an 'I' that knows guilt, pleasure and pain. These sensations are of course accompanied by electric signals in the brain that can be measured, and body and facial movements that can be observed. But while we can measure and observe signals and movements, we can never know another person's private subjective experience. Even if we can deduce what they are feeling we will never experience it ourselves, in the way that they do. Similarly, although we can perceive our own bodies (see, touch and feel them) that is quite different from seeing and touching through them.

In the same way, you may be aware that others exist by reading their thoughts as they appear on paper or on a screen, but having their thoughts is something unique to them. I cannot experience your thoughts. Even if I am able with some technical device to know what you are thinking, that is quite different from actually experiencing your thoughts as you do.

We all have an intuitive sense that we are more than just bodies ruled by physical and chemical laws; more than just complex stimulus-response machines. There is something about materialism that doesn't quite ring true with our experience.

This intuition could all be an illusion produced by brain biochemistry, but it could equally be true that there is some aspect of human existence which stands outside simple cause and effect, that human beings are in some sense 'supernatural'.

We already know that in the natural world things exist beyond our immediate perceptions, but within the perceptions of other species. For example dogs can hear high pitch sounds that are inaudible to humans, and birds can see colours we can't. Could it be that 'mind' is something that human beings will never be able to measure or fully.

Philosophers

• Plato (427-327BC) Ancient Greek philosopher and dualist
• Aristotle (384-322 BC) Ancient Greek philosopher and materialist
• Descartes, Rene (1596-1650) French philosopher and mathematician who defended mind-body dualism
• Spinoza, Baruch (1632-1677) Jewish philosopher and monist who held that only one substance called God or Nature exists
• Berkeley, George (1685-1753) British philosopher who defended idealism

Philosophers of mind have, for the last ten years, begun to question the possibility that science will ever be able to close the explanatory gap between the brain and our conscious experience. Chalmers(1) calls this 'the hard problem'. This gap could be so unbridgeable because mind and matter are in reality different. Some have called this position the new mysterians because they insist that mind/consciousness is fundamentally mysterious and cannot be explained by standard scientific means.(2)

But there is also a deeper logical problem with materialism. If we believe in a closed universe, where nothing but matter exists, then the human mind, by implication, becomes part of that closed cause and effect system. This leaves us having to believe that all our thoughts, including our belief in materialism, are simply determined by physics and biochemistry. But if we are simply determined to think that materialism is true, then how can we be sure that it really is true?

If we wish to retain any claim to objective knowledge, we must accept that the human mind has some independence from nature. But that would deny materialism!

Basis for respect

Another problem with materialism is that, it has led to a tendency to judge a person's worth by how clever they are. This results in us having no real basis for treating brain-damaged human beings any differently from animals. Bioethicist Peter Singer has put it quite starkly:

'Once the religious mumbojumbo surrounding the term human has been stripped away, we may continue to see 'normal' members of our species as possessing greater qualities of rationality, selfconsciousness, communication and so on than members of any others species, but we will not regard as sacrosanct the life of each member of our species, no matter how limited its capacity for intelligent or even conscious life may be'.(3)

Based on this belief Singer has been an advocate for infanticide, euthanasia and placing animal rights alongside human rights. These attitudes may shock us, but they do follow naturally from the belief that human beings are 'less than persons' if they have lost, or never gained, reasonable mental faculties.

Christian perspectives

The mind-body problem is complex. While Christians do not all agree on its solution, many take a dualist rather than a monist position. Christian researchers believe they are students both of the book of Nature (science) and the book of God (the Bible).

A Christian solution will be consistent with the science and also with the teaching of the Bible. What light does the Bible have to shed on the nature of human beings, and hence the mind-body problem? It tells us that human beings are godlike, complex, responsible and eternal - but also limited.

Godlike

God has a mind and yet doesn't need a body to act in the world. Similarly, although human bodies are part of the natural world, human beings also have minds, which to some extent, transcend the natural order, and yet can affect what happens in it. Being 'made in the image of God'(4) confers on us godlike qualities of creativity, rationality, personality, free will, selfawareness and consciousness and also gives us a special dignity, which deserves respect.(5)

Complex

The Bible describes man as consisting of spirit, soul and body.(6) But these components are not separate parts stuck together as in a 'lego kit'. Whilst Greek culture liked to separate spirit, soul and body, the Bible is strong in presenting human beings as a complex unity. Man was created by God to be a 'living being' composed both of the 'dust of the ground' and the 'breath of life'.(7) This tells us that we have both material and non-material aspects, but that they exist and belong together. Materialism, in contrast, tends to look for the simplest solution to issues.

Accountable

The Bible teaches that human beings can make real decisions, and are accountable for them. We are not simply ruled by nature or fate. This is why God can justifiably judge us. If we were just automatons and thereby the product of forces beyond our control, it would be unfair for God to hold us accountable for sin(8) (literally 'missing the mark'). This again implies that our minds are in some way outside the natural order.

Eternal

Our bodies die and yet the Bible teaches us that, despite this, human beings are eternal and live forever. The person survives death, implying that we are more than just bodies. But death does not lead to life as a disembodied spirit, or reincarnation. Rather, the Bible teaches that man's destiny is to die once and then face judgement(9) and either heaven or hell depending on our response to Jesus Christ.(10) People who have a relationship with God through Jesus will experience resurrection and live with God forever in a perfect 'new heaven and new earth',(11) with new resurrected bodies like that of Christ's after his resurrection.(12) This is clear from Jesus' pronouncement to the thief on the cross - 'Today you will be with me in paradise'.(13)

Limited

Finally, unlike God, human beings have finite power and knowledge. Despite our abilities we are limited in time and space. Even with sophisticated technology there are many things about the universe that we will never know. This does not give us an excuse for failing to ask questions or invoking God to explain the gaps in our knowledge. But we will recognise humbly that some things will always remain mysteries and beyond our understanding. Perhaps the mind-body problem is a mystery that is impossible for human minds to solve.

Conclusion

We may never fully unravel the intricacies of the mind-body problem, but we should be wary of too quickly embracing materialism. Materialism fails to explain our intuitive sense of self and has unwelcome implications for the way we should treat human beings. The Bible tells us that because human beings are made in God's image, they have real dignity, no matter how deformed the body or deranged the mind. They must therefore be treated with the utmost respect. The body has a natural end, but because human beings are eternal, there is hope of a better life to come after death, when the person survives, to be renewed and clothed by God with a new body in a perfect new world.

References

• Chalmers D. The Conscious Mind: In Search of a fundamental theory. Oxford University Press, 1996.
• Eliasmith C. Dualism. In Dictionary of Philosophy of Mind.
• Singer P. Sanctity of Life or Quality of Life? Paediatrics 1983; 72:128-9
• Genesis 1:26,27
• Genesis 9:5,6
• 1 Thessalonians 5:23
• Genesis 2:7
• Romans 3:23; 6:23
• Hebrews 9:27
• Revelation 20:11-15
• Revelation 21:1-5
• Philippians 3:21
• Luke 23:43

Bibliography

• Brown WS, Murphy N, Malony NH. Eds Whatever Happened to the Soul? Fortress Press, 1998
• Greenfield SA. The Human Brain: A guided tour. Weidenfield and Nicolson, 1999
• Gregersen NH, Drees WB, Gšrman U. The Human Person in Science and Theology. T&T Clark. 1997
• Jeeves M. Changing portraits of human nature. Science and Christian Belief. 2002;14:3-32
• Lewis CS. Miracles. New York: Macmillan, 1960. Reprinted by Fount, 1998
• Ryle G. The Concept of Mind. Hutchinson, 1949. Reprinted by Penguin, London, 1963
• Skinner BF. Beyond Freedom and Dignity. 1971. Penguin, 1973