The conundrum of mind and matter: what is consciousness?

Mind control: Inside Out is set in the brain of a girl, Riley, with her emotions played by five different actors.

It’s early in the morning and still dark outside. Your heart rate has dropped to a single beat per second and your blood pressure is the lowest it will be for the next 16 hours. Your respiration has fallen to 12 breaths a minute, while your blood glucose is at rock bottom. Despite the ingenious physiology remorselessly at work in all your organs, you sleep on, oblivious. In this state, your brain and body are preventing entry to a private inner universe that poses one of the biggest challenges in science – but any minute now, when the alarm buzzes, this special place will be all yours, exclusively.

However close you are to someone, however articulate, poetic, musical or compassionate you are, you will never, ever, be able to share your direct subjective experience with anyone else. But right now, for just a little longer, you are unconscious – “dead to the world”.

Without consciousness, life would indeed be pretty much the same as death. The conscious condition makes life worth living. But what is it, this insubstantial, intangible inner… what, exactly? Across the centuries, our predecessors have struggled to define and understand how to grapple with what is so intellectually elusive yet so familiar that we take it for granted day after day. Over the past 40 or 50 years, the issue has been thrown into ever sharper focus with the ascendance of neuroscience and the massive increase in our knowledge of the brain. But with this wealth of insight the problem becomes ever more glaring. How can your individual, subjective experience, within your physical brain, be translated into squirts of chemicals and electrical blips, and vice versa? What would prove definitive insight into consciousness?

However close you are to someone, you will never ever share your direct subjective experience

Perhaps the answer can be discovered in a brain scan. Or will the experience be pinned down in a mathematical formula? These “solutions” would never account for how objectively observable events turn into the first-hand feeling of a private experience. Somehow, a subjective perspective is generated – we could almost say “conjured up” – but no one has been able to explain how this apparent miracle takes place.

This tension between the objective and the subjective has seemed insoluble ever since the great philosopher René Descartes first raised it in the 17th century, when he chose to segregate a conscious mind from the biological brain. This conceptual chasm is tough to cross. When we describe a human being, or any animal, as having “perceptual experiences” or “conscious states”, we are talking about some of the most basic features which distinguish living from non-living things. A stone is not “about” anything and neither does it have subjective properties, but a perception is “about” what is seen (or experienced), such as what it is like to see the colour red.

These features are obvious to us from our first-person view, but when we shift perspective to the third-person stance of objective science we find ourselves in difficulty. We can speak of brain states, which may be reduced to neurons sparking and pulsing out chemicals, but it is hard to see how this neurobiological maelstrom relates to the features of consciousness that are so apparent in everyday experience – the taste of chocolate melting slowly in your mouth, the sunshine on your face, the sound of crashing waves. Small wonder that the black night outside your bedroom window is as nothing compared to the intellectual darkness that gives rise to this conceptual impasse.

A Day in the Life of the Brain by Susan Greenfield