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Can a mind ever know itself? Maybe we don't want to know: solving the 'hard problem' of consciousness could threaten our sense of self and free will

It is a concept so intrinsic to the fabric of our reality that starting to pick away at it leaves us feeling quite unravelled. "We can come closer to defining what it is to be an elephant than what it is to be conscious," says Nicholas Shea, who researches philosophy of the mind at the University of Oxford.

Consciousness is the essence of what it is to be "you". It is all your subjective experiences - from the feeling of the sun's warmth on your skin to the desolation of grief - conjured up somehow by your brain. "It still seems to many people, sometimes to me, very hard to see how things happening in the physical world could give rise to any sort of conscious experience at all," says neuroscientist Anil Seth at the University of Sussex, UK.

Explaining this phenomenon has been dubbed the "hard problem", and the worry is that we may be too close to it to ever figure it out. Thinking about consciousness means you have to be conscious - but can the human brain ever understand itself?

Shea thinks so. "It looks deep and complex and intractable, but people are applying the scientific method," he says. One school of thought is that if you can work out the physical brain activity that leads to, say, the visual experience of something being red, then you can generalise to other conscious experiences.

Another approach is what Seth calls a "divide and conquer" strategy. The aim here is to break consciousness down into different types of experience, he says: "what happens when you fall asleep and wake up; the relationship between visual perception and what's really out there; and you can also think about self and emotion." Tackling these problems one by one makes consciousness seem easier to grasp. "If you do that then, after a while, there'll be no remaining mystery," says Seth.

But others believe that even if you could map out the entire brain and what it was doing, you would still be in the dark about consciousness. "When it comes to explaining what it is to be me or you, we seem to want the kind of answer that we don't really ask for in other parts of science," says Seth. That may be because if we can crack how consciousness works, it threatens our sense of self and our notions of free will. "When you start to explain that voluntary actions and the experiences of intending to do things are just another kind of experience that depends on the brain, then you get quite a lot of resistance," he says.

One way out of this rabbit hole, says Seth, is to keep in mind what kind of free will is important. We want to be able to behave according to our beliefs and desires, which is possible no matter where conscious experience comes from. In other words, "I can choose what I want to do, but I can't choose what I want," he says.