Different Theories on Consciousness and the Brain

In his novel At Last, Edward St Aubyn imagines a philosopher sitting among the guests at someone’s funeral. He is so consumed with the problem of consciousness that every statement or observation made, no matter how innocent, raises new problems and fresh sets of questions. In spite of our many advances, the most fundamental reality of all, our conscious experience, remains a puzzle. As the Australian philosopher David Chalmers observed, “there is nothing that we know more intimately than conscious experience, but there is nothing that is harder to explain.”



Consciousness is a state of awareness. To be aware of what is going on outside or inside oneself is to be conscious. Thus it is a matter of personal experience – what it is like to be a certain way or feel a certain thing. Consciousness also suggests a sense of self. Even a parrot has consciousness: it is aware of the noise and danger outside and the pain and hunger inside. But does it have a sense of self? So far as we know it does not. Only humans seem to be aware that they are aware – conscious of their consciousness. A spider doesn’t plot and plan to catch a fly; it blindly acts out its evolutionary programming. In other words, it is not self-reflective; it doesn’t reflect on its actions.

When writing about human consciousness, people often refer to the “philosophical zombie,” a theoretical being who behaves and functions without subjective awareness. He eats scrambled eggs for breakfast, catches the number 73 bus to work, and spends all day selling fruit from a market stall. Yet there is no one ‘inside’ experiencing all this. Artificial intelligence would presumably work in the same way. If we could build a robot that caught the 73 bus, would it be aware of what it was doing? Would it be conscious that it was an intelligent being? Or would it simply go through the motions, like the spider and his web?

The Problem

In the last few decades we have learnt a huge amount about the brain. We know about synapses and neurotransmitters, and we understand how brain changes affect our experience of the world. But none of this explains conscious awareness. In fact, the more we learn about the brain, the more mysterious consciousness becomes.

When analyzing consciousness, people seem to end up with some kind of dualism: mind and brain, inner and outer, subjective and objective, spirit and matter, etc. Often, they begin with the materialist explanation. First, there was matter. Gradually, via the process of evolution, brains and nervous systems appeared. These brains and nervous systems are made from cells, and the cells are made of atoms. So matter precedes consciousness, and consciousness depends on matter.

Pick up a hot drink and hold it in your hand: smell the coffee, feel the smooth china surface, look at the flowery pattern. These experiences are unique. No one else can have exactly the same experience of that coffee cup as you. It smells and looks fractionally different to you as to your neighbor. You can explain your experience to one another, but no matter how eloquent you are it will always be limited and unsatisfactory. The point is that your consciousness is yours alone. Consciousness is a private, ineffable experience.

So you have two separate worlds. On the one hand, there is the cup of coffee out there in the world, occupying a position in time and space. On the other, here you are, having your own, private, intimate experience of it. In her book Consciousness, an Introduction, the British psychologist Susan Blackmore uses the example of a pencil instead of a coffee mug, concluding that “even with all my understanding of brain function, I cannot understand how subjective, private, ineffable suchness of experience, arises from an objective world of actual pencils and living brain cells. These subjective and objective worlds seem to be too different from each other to be related at all.”

The Brain

The brain is yet to be fully mapped and explained. Once it is, argue the materialists, consciousness will cease to be mysterious. For them, consciousness is the chemical and electrical activity of brains. The problem, they add, is not that consciousness is mysterious but that we cannot yet observe brain activity in sufficient detail. Those who oppose the materialists (sometimes known as the “mysterians”) claim that it’s irrelevant. You can dissect brains, attach electrodes, or place people in MRI scanners, none of it will unravel the essential mystery.

The materialists concede that a full explanation is not yet available. But they are closing in. And they are doing so step by step, analyzing “the neural correlates of consciousness.” In other words, the researcher studies some specific area of neural functioning and correlates it with specific conscious experiences. Eventually, they hope to link all conscious experience to a specific part of the brain.

The Materialist Explanation

In an interview with The Spectator magazine, the British neurosurgeon and author Henry Marsh remarked “everything we think and feel is electrochemical.” And that is a view most mainstream scientists share. The materialists would begin with the brain. Clearly, they argue, the brain is involved in conscious experience. I could cut off your legs and arms, and remove certain organs, but, so long as you survived, you would still be conscious. Remove the material object we call “the brain,” however, and conscious experience would cease.

The earth is very old. And it existed before any living thing crawled or flew across its surface. Life as we understand it is built from cells. But the first cells did not appear until long after the universe came into being. In other words, the earth existed before consciousness. Through comparative anatomy, we can see that the human brain resembles the brains of other animals. It therefore seems reasonable to conclude that evolution added layers to the brain that correspond to increased mental abilities.

In The Dragons of Eden, Carl Sagan also takes a firmly materialist line. Just as evolution is reflected in the development of the human foetus (at first fish-like, then reptilian, then mammalian, finally human), so it is in the structure of the brain. This is known as the Triune Brain. Sagan divides the brain into the “Reptilian Complex,” “Limbic System” and “Neocortex.” The first we share with reptiles, the second with other mammals. The Neocortex, however, makes us human. Through this addition, we have developed a sense of self and become aware of our instincts (rather than blindly acting upon them, as a wolf or snake does). As Sagan writes, the Neocortex is the place where “matter is transformed into consciousness.”

The American philosopher Daniel Dennett describes natural selection as a “universal acid,” eating away at any system or set of beliefs that does not take it into account. In essence, Darwin argued that life is a war. We compete for sex, power, food, etc. Anything that gives you an advantage will be favored by the law of natural selection. The creature with this trait then passes it on to its offspring. So, according to this law, consciousness must have helped our ancestors survive.

Non-Materialist Explanations

Of course, others disagree with the materialist approach. Even Henry Marsh, the English neurosurgeon quoted earlier, adds in his interview, “The thing is, we still don’t know what elevates matter in this way. We can’t explain the single most interesting thing in the world, which is our own consciousness.”

Dennett makes use of evolution, but so do the non-materialists. Pierre de Chardin, a French priest, believed that all life was struggling towards an “omega point” of higher consciousness. The philosopher Ken Wilber also takes an evolutionary approach, arguing for a hierarchical system in which insentient matter progresses or evolves towards superconsciousness.

In The Doors of Perception, Aldous Huxley speculates that the brain is like a radio, picking up consciousness as a radio picks up radio waves. Huxley uses the phrase “Mind at Large”. In theory, he writes, each individual could remember everything that ever happened to him and perceive everything that is occurring in the universe. Thus we are “each potentially Mind at Large.” But if we were subjected to that amount of consciousness the brain and nervous system would be paralyzed. Thus the brain exists to reduce and filter consciousness – to shut out Mind at Large. The materialist argues that there is survival value in consciousness, but there is also survival value in reducing consciousness. To survive, we need to focus on food, predators and mates.

The non-materialists use altered states of consciousness as evidence. Such altered states often involve a new sense of time. For example, people feel they are living in an “Eternal Now,” in which past, present and future exist simultaneously. There may also be a new sense of self. Instead of an ego, defined by its memories and hopes, people feel that all is one and that the ego prevents us realizing this. A new sense of meaning is also common. Suddenly, everything seems charged with significance. And the borders or limits of the body also seem to dissolve. Rather than feeling like an ego trapped inside a body, consciousness seems boundless and the body illusory.

When people experiment with psychedelic drugs, for example, their sense of separation dissolves and they feel connected to something greater. Unfortunately, we haven’t the language to describe these experiences. As Wittgenstein said, “the limits of your language are the limits of your world.” And our language evolved to deal with practical matters, with surviving here in the material world. Consequently, the insights people have in psychedelic, or altered, states cannot be translated into everyday speech.

The biologist Rupert Sheldrake is also critical of the materialist view, dismissing it as a product of the 19th century – just a phase in the history of ideas. In 18th century England, the Industrial Revolution led to unprecedented wealth. And that brought with it a new way of seeing the world: empirical, practical, and earth-bound. Only material objects had value, and that was reflected in 19th century philosophy.

Throughout most of human history, argues Sheldrake, people did not believe consciousness was restricted to the head. On the contrary, they believed that it extended throughout the body and beyond. Our consciousness linked us to dead ancestors, to the lives of animals and plants, even to the spirits and forces of nature (such as the wind or lightning). People also assumed that it could leave the body, especially during dreams, shamanic trances, and death itself. In 16th and 17th century Europe this view changed. Descartes and others argued that consciousness is located inside the head and restricted to human beings alone. Animals and plants were little better than machines.

Many non-materialist writers have drawn on 20th-century physics to back up their beliefs. The science is often difficult, involving things like “wave functions” and “microtubules,” but these theories have their supporters. Indeed, many of the great 20th-century physicists were interested in the parallels between modern physics and Eastern mysticism. For example, James Jeans, a physics professor who taught at Cambridge and Princeton, said “It may be that each individual consciousness ought to be compared to a brain cell in a universal mind.”

Some describe consciousness as the last great mystery. And it is astonishing that, in spite of our great advances, we cannot yet explain the most basic fact of all – our moment by moment awareness!

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