Live from TED

The hard problem of consciousness: David Chalmers at TED2014

Posted by:
David Chalmers. Photo: James Duncan Davidson

David Chalmers. Photo: James Duncan Davidson

“Right now you have a movie playing inside your head,” says philosopher David Chalmers. It’s an amazing movie, with 3D, smell, taste, touch, a sense of body, pain, hunger, emotions, memories, and a constant voice-over narrative. “At the heart of this movie is you, experiencing this, directly. This movie is your stream of consciousness, experience of the mind and the world.”

This is one of the fundamental aspects of existence, Chalmers says: “There’s nothing we know about more directly…. but at the same time it’s the most mysterious phenomenon in the universe.” What is the difference between us and robots? Nobody knows the answers.

For much of 20th century, Chalmers says, an idea that there could be no scientific study of consciousness held sway: Psychologists studied objective facts about behavior, neuroscientists studied the material of the brain. About 20 years ago that started to change. Prominent scientists like Francis Crick  and Roger Penrose started saying: Now is the time to attack this problem. “This has been wonderful, and great, but also has limitations.” Principally, the work so far has been a search for correlations between areas in the brain and conscious states. As he says, “This is still a science of correlations, not explanations.”

Chalmers believes the questions answered so far — mainly, about what parts of the brain do which bits of processing — are the “easy” (in comparison) problems. The hard problem is why is it that all that processing should be accompanied by this movie at all.

Many say that in a few years it will turn out that consciousness is just another emergent phenomenon, “like traffic jams or hurricanes or life, and we’ll figure it out.” But Chalmers believes there are limitations to this picture. Classic cases of emergence are all about behavior, about objective functioning. “You can apply that to the brain — how we walk, how we talk, how we play chess. But why is it that all this behavior is accompanied by subjective experience?”

Chalmers assures us he is a scientific materialist at heart, and that he wants a scientific theory of consciousness to work. But for a long time “I banged my head against the wall” until he concluded that what you get from a scientific theory of consciousness is always the objective behavior, but not the answer to the hard problem. “Faced with this, radical ideas might be needed. We might need one or two ideas that might seem crazy.”

Chalmers has a few candidates.

One crazy idea is from Daniel Dennett: There is no hard problem. The whole idea of the subjective movie is a kind of illusion. All we have to do is explain the objective behavior, and then we’re done. Chalmers respects the idea, but doesn’t like it: “I say more power to him, but for me that is too close to denying the datum of consciousness to be satisfying.”

So Chalmer’s own first crazy idea: consciousness is fundamental. “Physicists sometimes take parts of the universe as fundamental building blocks — space or time, or mass.” These are taken as primitive and the rest is built up from there. Sometimes the list of fundamentals expands, such as when James Clerk Maxwell realized that electromagnetism couldn’t be explained from other known laws of physics, and so he postulated electric charge as a new fundamental idea. Chalmers thinks that’s where we are with consciousness.

Importantly, “This doesn’t mean you suddenly can’t do science with it. This opens up the way to do science with it.” He thinks we need to connect this fundamental with the other fundamentals.

Chalmer’s second crazy idea: every system might be conscious at some level. Consciousness might be universal, an idea called panpsychism. The idea is not that photons are intelligent or thinking, or wracked with angst. Rather, it’s that “Photons have some element of raw subjective feeling, a precursor to consciousness.” Pause. “This might seem crazy to us,” he says, “but not to people from other cultures.”

But also, he goes on, a simple way to link consciousness to fundamental laws is to link it to information processing. It’s possible that wherever information is being processed, there is some consciousness. Chalmers put that idea forward about twenty years ago, but at the time it wasn’t well developed. Now a neuroscientist, Giulio Tononi, has created a measure, phi, that counts the amount of information integration. In a human, there is a lot information integration. In a mouse, still quite a lot. As you go down to worms, microbes and photons it falls off rapidly, but never goes to zero. “I don’t know if this is right, but right now it’s the leading theory.”

If true, this theory has many implications. “I used to think I shouldn’t eat anything that’s conscious. If you’re a panpsychist, you’ll be pretty hungry.” It’s also natural to ask about other systems, like computers. If consciousness is integrated information, and computers do integrate information, that raises ethical issues about developing intelligent computer systems, and turning them off.

Or you could think about bigger systems: “Does Canada have a consciousness? Or the TED audience? I don’t know the answer, but I think it’s one worth taking seriously.”

Chalmers closes by repeating that these are crazy ideas, designed to solve a hard problem, “It’s a radical idea, and I don’t know if it’s correct. This is the hardest problem in science and philosophy, so we aren’t going to figure it out overnight, but I do think we’re going to figure it out eventually.”