Body, Brain, Mind

Whoever wants to ask whether a machine can think must first say what it means for a human being to think. Here Part II of this book begins. Before consciousness, conscience, soul and dignity are discussed, a simpler question arises: how are body, brain and mind connected? Is the mind the brain at work, or is it more?

The word itself is of little help at first, for in German it means two things. “Geist” can denote the intellect, thinking, remembering and judging, in English “mind”. But it can also mean the spiritual side of the human being, the orientation towards God, in English “spirit”. Originally the Old High German “geist” meant agitation, being deeply moved. The Latin “spiritus” means breath; with it the Latin Bible rendered the Greek “pneuma” and the Hebrew “ruach”, both of which also mean wind and breath. Whoever asks whether a machine has “Geist” must therefore say which one they mean. The intellect it reproduces astonishingly well in many respects; whether it has a mind in this sense is the question of this chapter. Whether it can be deeply moved or oriented towards God is another question, and it leads to the soul (Chapter 6). In 1949 the philosopher Gilbert Ryle spoke mockingly of the “ghost in the machine” in order to criticise the notion that the mind dwells in the body like an invisible inhabitant. With artificial intelligence the image has taken a new turn: today people ask whether a mind could dwell in the machine. [Translator's note: The German “Geist” can mean mind and spirit, and also ghost; the sentence leaves these senses open.]

The sources of this book answer this question in very different ways. A physician and preacher describes the human being in three parts, a pastor speaks of the heart and of background assumptions, a philosopher of the porous and the buffered self, and natural science describes measurable processes in the brain. This chapter sets the answers side by side without declaring any one of them correct in advance. It does, however, test the claims that can be measured against what has been measured.

Enoch Sundaram, physician and preacher, describes the human being as created threefold: bodily, mental and spiritual. The mind, he says, is not the brain; the brain belongs to the body, while the mind is a realm of its own. [Translator's note: In Sundaram's model the German “Geist” spans both mind and spirit; it is rendered “mind” here and in what follows because the chapter treats his model as one answer to the question of the mind.] The most important part of creation, he says, is the mind, which is meant to direct the whole body. He compares it to the software of a computer, but stresses that this is only an image to aid understanding.

Sundaram divides the mind itself into two chambers. What science calls consciousness and the subconscious, he says, the Bible calls the outer and the inner realm. In consciousness, according to him, lie three capabilities: the power to think, conscience and the power to choose. The subconscious Sundaram calls the heart, the inner sanctuary of the soul; it is, he says, the holiest place in the human being.

This model has an astonishing closeness to the language of technology, and it has a strength of its own. It takes seriously that the human being is more than what they consciously think, and it connects the innermost layer of the human being with what is holiest to them. Chapter 4 examines this model more closely.

Timothy Keller, pastor and author, does not devise a model of the mind. He speaks of the heart in the language of the Christian tradition. He quotes Augustine, who wrote to God: You have created us towards yourself, and our heart is restless until it rests in you. The heart here is not an organ and not the subconscious, but the centre of the person, that towards which the person is oriented.

At the same time, Keller has an eye for what is at work below consciousness. Chapter 1 presented his thesis that barely conscious background assumptions determine which arguments convince at all. And he appeals to the old insight that self-knowledge and knowledge of God grow together and diminish together. On this understanding, the human being does not come to know themselves by looking inwards alone, but in relation to a counterpart.

Charles Taylor, philosopher, describes a shift in human self-understanding. The premodern self, he says, was porous: it knew no sharp boundary between its own interior and external spiritual forces. Its place was taken by the buffered self, to which it seems self-evident that all thinking, feeling and willing has its place in a psyche separated from the outside world. The notion of spirits and moral forces becomes increasingly incomprehensible to it. Where people used to say that someone was possessed by evil spirits, today we think of a mental illness.

This idea helps to place the models in this chapter. Sundaram's image of the heart as a sanctuary in which God wants to dwell belongs to the porous self. His language of programs and storage belongs to the buffered one. He combines the two, and this explains why his talks sound both devout and technical.

Against all these models stands a view that is widespread in contemporary philosophy. Physicalism holds everything to be physical or dependent on the physical. It does not deny that there are thoughts, feelings or moral judgements, but it traces them back to physical processes. On this view the mind is the brain at work, not a realm of its own.

A related view, functionalism, goes a step further. If the mind is a particular way of processing information, then it is not bound to the brain but could in principle also be realised in other material. Chapter 8 shows that a research group used precisely this assumption to test the consciousness of machines, and that the philosopher John Searle contradicted it. The question of body, brain and mind is thus at the same time the question of whether a machine can have a mind.

Whether the mind is a realm of its own, whether it emerges from the brain without being exhausted by it, or whether it is the brain itself, remains disputed in philosophy to this day. Positions in between, such as the view that the mind arises from the brain but cannot be reduced to its parts, have not yet been substantiated from specialist sources for this book.

Where the sources make statements about the brain, these can be tested. This is not a test of faith, but of the claims that are associated with it.

One important claim of Sundaram's is well established. In the past, he says, the brain was regarded as hard-wired; today it is known that it changes throughout life. No one, he says, is simply a victim of their biology. This corresponds to what research calls neuroplasticity. Eric Kandel, neuroscientist, received the Nobel Prize in 2000 for discoveries concerning how the connections between nerve cells change during learning. Long-term memory requires changes in protein synthesis and can alter the form and function of these connections; the activity of genes is involved.

Sundaram goes beyond this. Kandel, he says, showed that thoughts change DNA. That is an overextension. Learning changes which genes become active, not the genetic material itself. The difference is not hair-splitting. Whoever says that thoughts change DNA is claiming something that research does not show.

The same is true of sleep. That during sleep experiences are sorted and memory is consolidated is regarded as established. Sundaram says, beyond this, that new nerve cells are formed during sleep. Whether new nerve cells arise in the adult human brain to any appreciable extent at all has been openly disputed since 2018: one study found them absent or very rare, others found them into old age; differences in method are considered the likely explanation. None of the sources found makes a connection with sleep.

Some figures that play a large part in Sundaram's talks do not withstand scrutiny.

According to Sundaram, 2,000 processes take place in consciousness every second and 400 billion in the subconscious; this, he says, is what a physician and neuroscientist from the United States stated. This figure comes from popular sources, above all the film “What the Bleep” and books by Joe Dispenza, and there is no traceable measurement; one critic asks who claims to have counted these processes, and how. Research gives quite different orders of magnitude. According to a recent study, the sense organs take in around a billion bits per second, while behaviour processes only about ten. Research too, then, describes a large gap between what is taken in and what is consciously processed. The gap is real; the figures are not.

The same applies to the figure of around 70,000 thoughts a day. There is no research basis for it. The only measurement found counts the transitions between stable patterns of brain activity and arrives at about 6,200 a day.

Finally, Sundaram says that 90 per cent of all illnesses begin in the mind, and elsewhere he appeals to a study from Harvard according to which 87 to 93 per cent are psychologically caused. This study could not be found, and similar figures circulate without any basis. A widespread figure concerns visits to primary care that are related to stress, not the causes of illnesses.

This book does not cite these corrections in order to show Sundaram up. His theological statements do not depend on these figures. But whoever supports faith with false figures makes it vulnerable at a point where it need not be.

What lies behind the false figures is nevertheless not false. Research shows that emotions affect health, through behaviour and through the body's stress responses, and that, conversely, illness affects the emotions. Body and psyche are not separate realms but influence each other.

In a podcast conversation Sundaram draws a practical conclusion from this, which he grounds as a physician. Medicine, he says, is very good at repairing damage but pays too little attention to its causes; a patient receives a stent and, a few years later, a new blockage. People, he says, must be informed in such a way that they can make better decisions. Independently of his figures, he thereby makes a point that is important for this book: the human being is not simply a body on which something is repaired, but someone who decides how they live.

With this the question returns to the machine. A machine consists of processors, storage and programs. What this means for the question of the mind depends on which of the answers in this chapter one holds to be correct.

Whoever assumes that mind is nothing other than information processing must concede that a machine can in principle have a mind. A brain then processes signals, a computer processes signals, and the difference is one of material and construction, not of kind. This view corresponds to functionalism and is examined more closely in Chapter 8.

Whoever assumes, by contrast, that the mind is a realm of its own, as Sundaram says, or the centre of a person oriented towards a counterpart, as Keller describes it, comes to a different conclusion. Then a machine can reproduce what the mind does, language, calculation, remembering, without having what the mind is. A comparison makes this vivid: a translation program can render a love letter flawlessly without loving anyone. What the machine achieves is then genuine. What it lacks is just as genuine, and it cannot be replicated through greater performance.

Which answer is correct cannot so far be decided with the means of research. The following chapters therefore approach the question from different sides: through the unconscious, conscience and the soul.

And there is something else that distinguishes the human being, which has become visible in this chapter. A human being's mind is bound to a vulnerable, learning, ageing body that changes with every experience and that one day dies. Whether a system without such a body can have the same mind is open. Chapter 6 takes up this question again.