The Hard Problem of Consciousness

Why the redness of red is the thing physics cannot explain.

There is a question in philosophy of mind that, since David Chalmers named it in 1995, has gone by the title the hard problem of consciousness.¹ The hard problem is not whether the brain has neurons. It is not whether brain damage affects mental life. It is not whether you can correlate brain states with conscious experience.

The hard problem is this: why is there something it is like to be you?

When light at 700 nanometers hits your retina, a cascade of biochemistry runs in your visual cortex, and you have an experience we call seeing red. The biochemistry is, in principle, completely describable in the language of physics. We can trace every photon, every neurotransmitter, every action potential.

But none of that describes the redness. The what-it-is-like-ness of seeing red — what philosophers call qualia — is not, in any obvious sense, a physical fact. It is a fact about the experience that accompanies the physical facts.

And here is the puzzle. On a purely physical view of the universe, there should not be such an experience at all. The biochemistry, by itself, should run in the dark. The lights should not be on inside.

But the lights are on. You can verify this right now. You know what your own consciousness is, in a way you know almost nothing else.

Why this is hard for materialism

Materialism is the view that the universe is, in the end, only matter — that everything is reducible, in principle, to physics. On this view, your consciousness is identical to some pattern of electrochemical activity in your brain. Not just correlated with. Identical to.

The hard problem is that the identity does not look like an identity. It looks like a juxtaposition. Here is a pattern of activity. Here is an experience. We have a hundred years of careful research showing that the pattern predicts the experience, that damage to the pattern disrupts the experience, that the pattern correlates with the experience.

What we do not have is any account, in the language of physics, of why the pattern is the experience. There is, in Joseph Levine’s phrase, an explanatory gap between the physical description and the phenomenal reality.²

You can imagine, perfectly coherently, a being who is physically identical to you in every detail but with no inner experience at all — a philosophical zombie, in the technical literature. The fact that such a being is even conceivable tells you that consciousness is not logically reducible to physics. There is a genuine extra fact about you that the physics, however complete, does not capture.

The standard responses

Materialists have not been silent in the face of this. The three main responses:

Eliminativism. There is no hard problem, because there is no consciousness in the sense you think. The redness of red is an illusion produced by your introspection; the actual fact is just the biochemistry. Daniel Dennett has been the most prominent defender of this move.

This is a self-undermining position. You have to use consciousness to deny consciousness. The argument I am directly aware that my introspective awareness is mistaken has the same form as this sentence is false. It is also, frankly, not what most people are prepared to say when they sit honestly with their own experience of being alive.

Functionalism. Consciousness just is a certain kind of information-processing function. Anything that processes information in the right way is conscious; the redness of red is what it is like to be the processor.

This is more sophisticated, but it does not, on inspection, dissolve the puzzle. It just relocates it. Why is that kind of information processing accompanied by experience, while other kinds (the information processing in a thermostat, or in a Roomba, or in the weather system) seemingly are not? The functionalist owes us an account of the bridge, and the account, when offered, turns out to be a list of correlates rather than an explanation.

Property dualism / panpsychism. Consciousness is a fundamental property of the universe, not reducible to physics. Either certain arrangements of matter have it (property dualism) or all matter has some primitive form of it (panpsychism).

This is the position more and more honest materialists are drifting toward. It is, in my reading, not really materialism anymore. It is the admission that the physical story is incomplete and something else has to be added. That something else is, in the panpsychist case, embarrassingly close to spirit.

What this means for the theistic case

The hard problem of consciousness is, I think, one of the strongest arguments for a non-materialist worldview that the modern academy has produced. And it has been produced largely by atheists, working inside the materialist tradition, who could not get the materialism to add up.

It does not, by itself, prove God. But it does the same thing the moral argument does: it shows that the world has features — real, persistent, unignorable features — that fit awkwardly into the materialist picture and fit naturally into the theist picture. On the Christian view, consciousness is exactly what we would expect: the universe was made by a conscious God, who made conscious creatures in his image. The world has a mind in it because the maker of the world has a mind.

You can keep adding these arguments together. None of them is decisive on its own. Taken together, they constitute the cumulative case that the Christian picture fits the world better than the alternatives. The moral argument and the hard problem of consciousness are two pieces of that case.