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In Cotard鈥檚 syndrome, the feeling of existence corrodes but something more fundamental does not (see 鈥�How do I know I exist鈥�). Even though people with this rare condition feel they don鈥檛 exist, there is still an 鈥淚鈥� experiencing that feeling. What is that 鈥淚鈥�? One answer is that it may be a by-product of consciousness itself.

Read more: What is consciousness?

How your brain creates the feeling of being is the biggest problem in neuroscience. But we are coming closer to cracking it

Ren茅 Descartes was convinced that the body and conscious mind are two different substances: the first is made of matter, the latter is immaterial. His ideas influenced neuroscience until a few decades ago, but the field has moved on. Today, it is widely accepted that our brains give rise to consciousness.

But how? That is a raging debate. At its heart is what philosopher David Chalmers at New York University termed the 鈥渉ard problem鈥� of consciousness: how can physical networks of neurons produce experiences that appear to fall outside the material world? As Thomas Nagel, also at New York University, put it in the 1970s: you could know every detail of the physical workings of a bat鈥檚 brain, but still not know what it is like to be a bat.

鈥淵ou may know beyond a doubt that you exist, but your 鈥業鈥� could still be an illusion鈥�

Broadly speaking, those trying to solve the hard problem fall into two camps, according to psychologist and philosopher Nicholas Humphrey. There are those who think that consciousness is something real and those who say it鈥檚 a mirage, and so dismiss the problem entirely.

Mind trickery

The former camp argues that consciousness is a fundamental component of the universe, one that exists alongside matter and has properties which, perhaps conveniently, cannot be explained by our present understanding of physics. If taken to the extreme, says Chalmers, this idea can lead to panpsychism, the view that all matter 鈥� even inanimate objects like rocks 鈥� is imbued with some degree of consciousness.

Even without tackling that particular Pandora鈥檚 box, this camp faces a daunting challenge. We know that conscious thought can influence the body. A conscious desire to move your arm results in physical movement. But the fundamentals of how this happens remain hazy.

Those on the other side say the hard problem creates one where there is none. 鈥淚t鈥檚 an unsolvable mystery, because the problem is ill posed,鈥� says neuroscientist Michael Graziano of Princeton University. He argues that consciousness is nothing but a trick of the mind. What鈥檚 more, the brain doesn鈥檛 just create the illusion of consciousness but also the feeling that there is a separate, immaterial 鈥淚鈥� having a conscious experience. In other words: there is no need to explain strange interactions between material and immaterial things because the immaterial things don鈥檛 really exist.

For Graziano, Tufts University philosopher Daniel Dennett and other 鈥渕aterialists鈥�, the real issue is not solving the hard problem but explaining how the brain accomplishes this trickery. Graziano resolves this by saying that consciousness is 鈥渢he brain鈥檚 way of describing to itself what it means to pay attention to and deeply process a signal鈥�.

The argument goes like this: we must pay attention to our environment to survive. As a result, our brains have become very skilled at representing the world around us. Somewhere in the course of evolution, they began representing objects as having immaterial properties, and in so doing it generated the mirage of consciousness.

Ultimately, most materialists take the view that after we die and our brains and bodies have decomposed, there is nothing left. That must mean that our prevailing sense of a separate, immaterial 鈥淚鈥� was also an illusion.

Which brings us back to the previous question: although you may know beyond doubt that you exist 鈥� and indeed it is very possible that you are not a simulation 鈥� the 鈥淚鈥� you perceive yourself to be could still be an illusion.

This article appeared in print under the headline 鈥淲hat is consciousness?鈥�