10/15/2012 04:47 pm ET Updated Dec 15, 2012

The Enigma of Human Consciousness

On Oct. 10 I attended a panel discussion at the New York Academy of Sciences titled "The Thinking Ape: The Enigma of Human Consciousness." The panel was presented by the NYAS, the Nour Foundation and To the Best of Our Knowledge, a nationally syndicated program on Wisconsin Public Radio.

The panel: David Chalmers, the well-known philosopher of mind; Daniel Kahneman, the well-known cognitive psychologist and Nobel laureate; Laurie Santos, a bright young psychologist at Yale who studies primate cognition; Nicholas Schiff, a neurologist who studies disorders of consciousness; and the moderator, Steve Paulson, the host of To the Best of Our Knowledge.

I jotted down a few notes. Here they are, with comments. (Everything not in quotation marks is paraphrased.)

Chalmers: Roughly, science progresses along a spectrum. Physics explains chemistry, which explains biology, which explains psychology, which explains sociology. Consciousness is a problem for science because it doesn't fit in that spectrum.

Santos: Fifty years ago there would have been behaviorists up here saying the human mind is a black box and impossible to understand. Now we understand the mind much better. Maybe in another 50 years a new tool will help us understand consciousness and we'll view today's pessimism as foolish.

Kahneman: I'm in the minority in that I've never been very interested in explaining consciousness. It's hard to be interested in a question if you don't even know the structure of a possible answer.

Chalmers: Right now all we can do is match brain states to behavior and to reported experience. Currently consciousness studies is a science of correlation, not explanation. [To me, this was the comment of the night. I also think consciousness studies will always be a science of correlation. Later there was an interesting digression on whether all science, even physics, was a science of correlation, and whether having enough correlations counts as an explanation.]

Kahneman: We'll have robots that appear conscious before we can explain consciousness.

Chalmers: I'll be convinced a computer is conscious when it says it's having trouble explaining why it has subjective states.

Kahneman: I don't think being a philosopher is an indicator of consciousness. [Ha ha. He was teasing (I think), but it's a valid point. Aside from the obvious fact that a computer can easily be programmed to automatically spit out "Why am I conscious?," an unconscious entity can raise genuine questions about internal anomalies that give rise to such outputs as "Why am I conscious?"]

Kahneman: Emotions are important in attributions of consciousness. [I'm not sure if by emotions he meant the recognition of emotions in the subject, or the observer's emotional response to the subject's behavior. Either way, I agree. An intelligent but cold A.I. would not necessarily be seen as conscious, and targets such as babies that trigger empathy trigger anthropomorphism.]

Schiff: Right now there's a lot of work on minimally conscious states. Certain reactions, such as tracking movement with the eyes, don't necessarily imply consciousness, but we can infer that they might, given that they correlate with later recovery.

Santos: In work on animal cognition, people are starting to think that it's not just cognitive abilities such as language that separate humans from other animals, but it's our motivation to communicate. [See, for instance, this chapter by anthropologist Michael Tomasello. Santos also made the funny remark that if a bird could carry on a conversation, she doubts it would have anything interesting to say -- meaning that it's more than just language that sets us apart. My thought was that sustaining human-level language capabilities would probably require a great deal of brain complexity, and thus general intelligence, so the bird probably would be worth chatting up after all. But there are debates about the modularity of cognition.]

Chalmers: I'm sympathetic to panpsychism, the perspective that consciousness, or "proto-consciousness," is an irreducible part of the universe, like matter, and that it is present not just in the brain but everywhere. [I recommend science writer Jim Holt's essay "Mind of a Rock."]

Schiff: The hypothesis that science cannot explain consciousness is a reasonable one, but not an interesting one. It doesn't give us anything to do. I prefer to bracket it off and carry on like it's false.

Kahneman: Regarding things that can be conscious, "I see no reason it has to be made of meat." [In other words, why it must be a brain. Here they discuss whether consciousness is best explained in terms of information processing rather than physical processes. I think the approach with the most promise in this realm is Giulio Tononi's integrated information theory. But information theories can't explain why consciousness emerges from unconscious matter to begin with -- what Chalmers has called "the hard problem of consciousness."]

Chalmers: Danny, if, one by one, we replaced your neurons with functional equivalents made of silicon, would you be conscious? [I'm not enthusiastic about thought experiments in which human consciousness is run on machinery other than the human brain, because I think such propositions miss something. I don't believe two identical states of consciousness in principle require two identical physical substrates, but I suspect that they do in fact. A computer simulating all the functionality of a single neuron would, in order to approach its efficiency, have to become smaller and smaller and more and more like a neuron until it in fact became a neuron. The same might go for reproducing the functionality of the brain as a whole.]

Audience member: What are your definitions of consciousness?

Chalmers: The best we can do is to say, as Thomas Nagel does, that it is something it is like to be. We can talk about what it is like to be me, or a bat, but not this water bottle.

Santos: If the philosopher can't define it, I'm not going to try.

Kahneman: We can't define consciousness, only our intuitions about it.

Audience member: What's the purpose of defining consciousness?

Schiff: One practical use is in treating brain-damaged patients. When do we give up on them? The science of who is and who is not conscious is becoming more uncertain, making such decisions harder.

Audience member: Is it possible to have an objective science of subjectivity?

Chalmers: Yes, you can state facts about feelings. Also, first-hand experience is important to the science of consciousness.

Kahneman: I don't think anyone is protesting that. [True, but I might add an asterisk and make the point that, technically, it's third-party observations of people reporting first-hand experiences that are important. The first-hand experiences themselves are inherently unsuitable as scientific data; by definition they can be experienced by only one person, and scientific observations need to be reproducible.]

Kahneman: The best response to paradoxes is to simply walk away. [Don't recall what this was in response to, but it's solid advice.]

Audience member: We've been hearing a lot about scientists. Which writers have offered the most insight into consciousness?

Chalmers: "Proust is a master phenomenologist."

Schiff: In Helen Keller's book Teacher, she said she did not have a self before she learned language; she was a "phantom."

Paulson: William James is my hero.

[A couple of panelists mention Oliver Sacks.]

Audience member: What is the purpose of consciousness?

Chalmers: No one knows. We might as well be zombies.

* * * * *

Surprisingly, the phrase "free will" was never uttered, although I saw it on the horizon when the topic of the function of consciousness came up. For the record, I think consciousness has no function; it's a side effect, or "epiphenomenon," of neural processes. We might as well be zombies indeed. (For research on the function of psychological processes that happen to give rise to consciousness, see Roy Baumeister, although in his language he ascribes this functionality to consciousness itself.)

Also, Paulson asked whether self-awareness is possible without consciousness. This one is easy. If by "self-awareness" one means self-consciousness, the answer is no. You can't be conscious of your consciousness if you have no consciousness to be conscious of. But if by "self-awareness" one means simply a capacity for internal feedback, the answer is yes. Any machine that monitors its own functioning could be said to be self-aware, without being conscious (but see: panpsychism). A harder question is whether one can have consciousness without self-consciousness. Can you have a subjective state without being able to reflect on it? I'll let you think on that one. In the meantime, beware of the unicorn.