The Hard Problem of Consciousness: Why Science Is Stuck

Neo is a programmer with an ordinary life until a man named Morpheus tells him it isn’t. The world he has trusted his whole life turns out to be a rendering. His hands are not hands. The floor is not a floor.

Christopher Nolan built Inception on the same anxiety. Cobb moves through other people’s dreams and cannot always tell which layer he is standing on, so he carries a small spinning top to test the ground under his feet.

Both films work because the fear is real. Can you prove, right now, that the eyes reading this sentence exist? Serious physicists have argued that the universe may be a simulation, and philosophers have entertained the idea that everything you perceive is generated by a brain floating somewhere with no body attached.

Held to the standard of absolute proof, you cannot demonstrate that your body exists, or your phone, or the chair you are sitting in. But something survives the doubt. Whatever else is uncertain, there is someone to whom things are appearing. The dream may be false. The dreamer is not.

Descartes got here first. He doubted everything he could, including his own body, and found one thing he could not get behind: a thing that doubts must exist in order to do the doubting. I think, therefore I am.

That leftover — the fact that there is something it is like to be you — is the subject of this article. It is also, by the admission of the people who study it for a living, the hardest unsolved problem in science.

Two very different questions

Think about someone watching a horror film. There are two questions you could ask.

How does the retina encode light, route the signal to the visual cortex, trigger the amygdala, and raise the heart rate? That question is difficult, but it is the kind of difficult that neuroscience gets better at every year.

Why is any of it felt? Why is there fear, rather than an efficient threat-response running in the dark with nobody home?

The second question is a different species altogether, and no amount of progress on the first has moved it. In 1995 the philosopher David Chalmers named it the hard problem. Nobody, he argued, can seriously deny that creatures have subjective experience. What remains mysterious is why any physical system should produce it at all.

Chalmers is not a religious believer. He is an atheist who concluded that physics alone does not have the resources for this, and the most influential statement of the problem comes from someone with no theological motive whatsoever.

A bet, a case of wine, and twenty-five years

In the 1990s the neuroscientist Christof Koch was as confident a reductionist as the field had. At a conference in Tucson he confronted Chalmers at a cocktail party, told him his theory of consciousness was untestable and therefore useless, and shot back that Chalmers might as well say the Holy Ghost descends and makes you conscious.

In 1998 Koch put money behind the confidence. He bet Chalmers a case of fine wine that within twenty-five years neuroscience would identify the mechanism underlying consciousness.

In June 2023, at a conference in New York, Koch conceded and handed over the wine. The mechanism had not been found.

He is not alone in the admission. Edward Witten, one of the most formidable living physicists, has said he finds the Big Bang easier to think about than consciousness and expects it to remain a mystery. The late Jaegwon Kim spent a career defending physicalism and still granted that sensation and feeling resist physical explanation in a way that thinking does not. Ned Block, asked why so many careful people end up as dualists, answered that we have no conception at all of how to get consciousness out of matter.

What has to be given up

Watch what happens when the explanation is not available but the commitment is non-negotiable. Something has to be denied — and the interesting thing is that no two thinkers deny the same thing.

Each is a serious position held by a serious person. But between them they have surrendered nearly everything an ordinary person would list if you asked what a mind is. The materialist account is not one theory with one cost. It is a set of incompatible bargains, each paid for in a different currency.

And notice the third one especially. Rosenberg denies that thoughts are about things because he is being consistent: no physical arrangement is intrinsically about anything. Ink is not about anything; we assign it meaning. Magnetised regions on a disk are not about anything; a convention makes them so. Physical states have causes and effects. They do not have subjects.

Yet right now your thinking is directed at this sentence. Later today it will be directed at someone you love. You know this from the inside, and no argument is going to talk you out of it.

Which explanation is doing better?

None of this is a proof, and I would rather not pretend otherwise. Nobody can hand you a syllogism about consciousness that a determined sceptic cannot resist.

But this much is on the table:

• Consciousness is the one thing you cannot coherently doubt.
• The people working hardest on it say, in their own words, that they cannot explain it — and one of them bet his career timeline on it and lost.
• Keeping materialism intact has required denying the felt quality of experience, or the self, or free will, or the aboutness of thought.

Meanwhile there is an explanation available that costs none of that. If a conscious God made conscious beings, then first-person experience is not an anomaly waiting on a theory. It is exactly what you would expect. Minds come from a mind.

You are not obliged to accept it. But look at how the alternatives are faring. Faced with a fine-tuned universe, some prefer an infinite ensemble of universes nobody has observed. Faced with the odds against life assembling by chance, some prefer to wait for a mechanism not yet found. Faced with consciousness, some now prefer to say the internet might be having an experience.

Every one of those is a choice. Each rules out one particular explanation in advance and then pays whatever the remaining options cost. It is worth asking what is doing the ruling out.