How do you explain consciousness?
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0:01 - 0:03Right now
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0:03 - 0:06you have a movie playing inside your head.
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0:06 - 0:09It's an amazing multi-track movie.
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0:09 - 0:12It has 3D vision and surround sound
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0:12 - 0:14for what you're seeing and hearing right now,
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0:14 - 0:17but that's just the start of it.
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0:17 - 0:22Your movie has smell and taste and touch.
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0:22 - 0:25It has a sense of your body,
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0:25 - 0:29pain, hunger, orgasms.
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0:29 - 0:31It has emotions,
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0:31 - 0:34anger and happiness.
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0:34 - 0:38It has memories, like scenes from your childhood
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0:38 - 0:41playing before you.
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0:41 - 0:45And it has this constant voiceover narrative
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0:45 - 0:50in your stream of conscious thinking.
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0:50 - 0:55At the heart of this movie is you
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0:55 - 0:59experiencing all this directly.
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0:59 - 1:05This movie is your stream of consciousness,
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1:05 - 1:06the subject of experience
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1:06 - 1:11of the mind and the world.
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1:11 - 1:14Consciousness is one of the fundamental facts
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1:14 - 1:16of human existence.
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1:16 - 1:19Each of us is conscious.
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1:19 - 1:21We all have our own inner movie,
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1:21 - 1:24you and you and you.
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1:24 - 1:28There's nothing we know about more directly.
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1:28 - 1:31At least, I know about my consciousness directly.
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1:31 - 1:35I can't be certain that you guys are conscious.
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1:35 - 1:39Consciousness also is what makes life worth living.
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1:39 - 1:42If we weren't conscious, nothing in our lives
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1:42 - 1:46would have meaning or value.
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1:46 - 1:47But at the same time, it's the most
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1:47 - 1:51mysterious phenomenon in the universe.
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1:51 - 1:54Why are we conscious?
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1:54 - 1:56Why do we have these inner movies?
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1:56 - 1:58Why aren't we just robots
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1:58 - 2:00who process all this input,
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2:00 - 2:02produce all that output,
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2:02 - 2:06without experiencing the inner movie at all?
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2:06 - 2:09Right now, nobody knows the answers
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2:09 - 2:11to those questions.
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2:11 - 2:14I'm going to suggest that to integrate consciousness
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2:14 - 2:19into science, some radical ideas may be needed.
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2:19 - 2:22Some people say a science of consciousness
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2:22 - 2:24is impossible.
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2:24 - 2:28Science, by its nature, is objective.
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2:28 - 2:31Consciousness, by its nature, is subjective.
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2:31 - 2:36So there can never be a science of consciousness.
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2:36 - 2:39For much of the 20th century, that view held sway.
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2:39 - 2:43Psychologists studied behavior objectively,
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2:43 - 2:47neuroscientists studied the brain objectively,
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2:47 - 2:50and nobody even mentioned consciousness.
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2:50 - 2:53Even 30 years ago, when TED got started,
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2:53 - 2:55there was very little scientific work
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2:55 - 2:58on consciousness.
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2:58 - 3:00Now, about 20 years ago,
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3:00 - 3:03all that began to change.
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3:03 - 3:05Neuroscientists like Francis Crick
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3:05 - 3:08and physicists like Roger Penrose
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3:08 - 3:10said now is the time for science
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3:10 - 3:13to attack consciousness.
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3:13 - 3:15And since then, there's been a real explosion,
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3:15 - 3:18a flowering of scientific work
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3:18 - 3:19on consciousness.
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3:19 - 3:21And this work has been wonderful. It's been great.
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3:21 - 3:23But it also has some fundamental
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3:23 - 3:27limitations so far.
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3:27 - 3:29The centerpiece
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3:29 - 3:31of the science of consciousness in recent years
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3:31 - 3:34has been the search for correlations,
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3:34 - 3:37correlations between certain areas of the brain
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3:37 - 3:41and certain states of consciousness.
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3:41 - 3:42We saw some of this kind of work
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3:42 - 3:44from Nancy Kanwisher and the wonderful work
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3:44 - 3:47she presented just a few minutes ago.
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3:47 - 3:51Now we understand much better, for example,
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3:51 - 3:53the kinds of brain areas that go along with
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3:53 - 3:56the conscious experience of seeing faces
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3:56 - 4:00or of feeling pain
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4:00 - 4:02or of feeling happy.
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4:02 - 4:05But this is still a science of correlations.
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4:05 - 4:08It's not a science of explanations.
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4:08 - 4:11We know that these brain areas
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4:11 - 4:15go along with certain kinds of conscious experience,
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4:15 - 4:18but we don't know why they do.
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4:18 - 4:21I like to put this by saying
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4:21 - 4:24that this kind of work from neuroscience
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4:24 - 4:26is answering some of the questions
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4:26 - 4:28we want answered about consciousness,
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4:28 - 4:32the questions about what certain brain areas do
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4:32 - 4:34and what they correlate with.
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4:34 - 4:37But in a certain sense, those are the easy problems.
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4:37 - 4:39No knock on the neuroscientists.
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4:39 - 4:42There are no truly easy
problems with consciousness. -
4:42 - 4:46But it doesn't address the real mystery
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4:46 - 4:48at the core of this subject:
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4:48 - 4:53why is it that all that physical processing in a brain
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4:53 - 4:56should be accompanied by consciousness at all?
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4:56 - 4:59Why is there this inner subjective movie?
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4:59 - 5:02Right now, we don't really have a bead on that.
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5:02 - 5:04And you might say,
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5:04 - 5:08let's just give neuroscience a few years.
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5:08 - 5:11It'll turn out to be another emergent phenomenon
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5:11 - 5:16like traffic jams, like hurricanes,
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5:16 - 5:19like life, and we'll figure it out.
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5:19 - 5:21The classical cases of emergence
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5:21 - 5:24are all cases of emergent behavior,
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5:24 - 5:27how a traffic jam behaves,
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5:27 - 5:28how a hurricane functions,
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5:28 - 5:30how a living organism reproduces
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5:30 - 5:34and adapts and metabolizes,
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5:34 - 5:36all questions about objective functioning.
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5:36 - 5:39You could apply that to the human brain
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5:39 - 5:41in explaining some of the behaviors
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5:41 - 5:43and the functions of the human brain
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5:43 - 5:44as emergent phenomena:
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5:44 - 5:48how we walk, how we talk, how we play chess,
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5:48 - 5:50all these questions about behavior.
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5:50 - 5:52But when it comes to consciousness,
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5:52 - 5:54questions about behavior
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5:54 - 5:57are among the easy problems.
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5:57 - 5:59When it comes to the hard problem,
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5:59 - 6:01that's the question of why is it
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6:01 - 6:03that all this behavior
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6:03 - 6:06is accompanied by subjective experience?
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6:06 - 6:08And here, the standard paradigm
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6:08 - 6:09of emergence,
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6:09 - 6:12even the standard paradigms of neuroscience,
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6:12 - 6:17don't really, so far, have that much to say.
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6:17 - 6:20Now, I'm a scientific materialist at heart.
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6:20 - 6:24I want a scientific theory of consciousness
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6:24 - 6:27that works,
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6:27 - 6:29and for a long time, I banged my head
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6:29 - 6:31against the wall
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6:31 - 6:33looking for a theory of consciousness
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6:33 - 6:35in purely physical terms
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6:35 - 6:36that would work.
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6:36 - 6:38But I eventually came to the conclusion
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6:38 - 6:42that that just didn't work for systematic reasons.
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6:42 - 6:44It's a long story,
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6:44 - 6:46but the core idea is just that what you get
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6:46 - 6:49from purely reductionist explanations
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6:49 - 6:51in physical terms, in brain-based terms,
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6:51 - 6:54is stories about the functioning of a system,
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6:54 - 6:56its structure, its dynamics,
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6:56 - 6:58the behavior it produces,
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6:58 - 7:00great for solving the easy problems —
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7:00 - 7:02how we behave, how we function —
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7:02 - 7:06but when it comes to subjective experience —
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7:06 - 7:09why does all this feel like
something from the inside? — -
7:09 - 7:11that's something fundamentally new,
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7:11 - 7:15and it's always a further question.
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7:15 - 7:21So I think we're at a kind of impasse here.
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7:21 - 7:24We've got this wonderful, great chain of explanation,
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7:24 - 7:27we're used to it, where physics explains chemistry,
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7:27 - 7:31chemistry explains biology,
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7:31 - 7:35biology explains parts of psychology.
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7:35 - 7:36But consciousness
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7:36 - 7:39doesn't seem to fit into this picture.
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7:39 - 7:41On the one hand, it's a datum
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7:41 - 7:43that we're conscious.
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7:43 - 7:44On the other hand, we don't know how
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7:44 - 7:48to accommodate it into our
scientific view of the world. -
7:48 - 7:50So I think consciousness right now
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7:50 - 7:52is a kind of anomaly,
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7:52 - 7:54one that we need to integrate
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7:54 - 7:58into our view of the world, but we don't yet see how.
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7:58 - 8:00Faced with an anomaly like this,
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8:00 - 8:03radical ideas may be needed,
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8:03 - 8:06and I think that we may need one or two ideas
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8:06 - 8:09that initially seem crazy
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8:09 - 8:12before we can come to grips with consciousness
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8:12 - 8:14scientifically.
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8:14 - 8:15Now, there are a few candidates
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8:15 - 8:18for what those crazy ideas might be.
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8:18 - 8:22My friend Dan Dennett, who's here today, has one.
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8:22 - 8:25His crazy idea is that there is no hard problem
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8:25 - 8:26of consciousness.
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8:26 - 8:30The whole idea of the inner subjective movie
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8:30 - 8:34involves a kind of illusion or confusion.
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8:34 - 8:36Actually, all we've got to do is explain
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8:36 - 8:39the objective functions, the behaviors of the brain,
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8:39 - 8:41and then we've explained everything
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8:41 - 8:44that needs to be explained.
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8:44 - 8:46Well I say, more power to him.
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8:46 - 8:48That's the kind of radical idea
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8:48 - 8:50that we need to explore
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8:50 - 8:53if you want to have a purely reductionist
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8:53 - 8:56brain-based theory of consciousness.
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8:56 - 8:58At the same time, for me and for many other people,
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8:58 - 9:00that view is a bit too close to simply
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9:00 - 9:02denying the datum of consciousness
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9:02 - 9:04to be satisfactory.
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9:04 - 9:07So I go in a different direction.
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9:07 - 9:08In the time remaining,
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9:08 - 9:11I want to explore two crazy ideas
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9:11 - 9:15that I think may have some promise.
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9:15 - 9:16The first crazy idea
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9:16 - 9:21is that consciousness is fundamental.
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9:21 - 9:24Physicists sometimes take
some aspects of the universe -
9:24 - 9:26as fundamental building blocks:
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9:26 - 9:30space and time and mass.
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9:30 - 9:33They postulate fundamental laws governing them,
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9:33 - 9:37like the laws of gravity or of quantum mechanics.
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9:37 - 9:39These fundamental properties and laws
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9:39 - 9:43aren't explained in terms of anything more basic.
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9:43 - 9:45Rather, they're taken as primitive,
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9:45 - 9:49and you build up the world from there.
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9:49 - 9:54Now sometimes, the list of fundamentals expands.
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9:54 - 9:56In the 19th century, Maxwell figured out
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9:56 - 10:00that you can't explain electromagnetic phenomena
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10:00 - 10:02in terms of the existing fundamentals —
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10:02 - 10:05space, time, mass, Newton's laws —
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10:05 - 10:08so he postulated fundamental laws
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10:08 - 10:09of electromagnetism
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10:09 - 10:12and postulated electric charge
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10:12 - 10:14as a fundamental element
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10:14 - 10:16that those laws govern.
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10:16 - 10:20I think that's the situation we're in
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10:20 - 10:21with consciousness.
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10:21 - 10:24If you can't explain consciousness
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10:24 - 10:26in terms of the existing fundamentals —
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10:26 - 10:29space, time, mass, charge —
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10:29 - 10:32then as a matter of logic,
you need to expand the list. -
10:32 - 10:35The natural thing to do is to postulate
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10:35 - 10:38consciousness itself as something fundamental,
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10:38 - 10:41a fundamental building block of nature.
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10:41 - 10:44This doesn't mean you suddenly
can't do science with it. -
10:44 - 10:48This opens up the way for you to do science with it.
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10:48 - 10:50What we then need is to study
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10:50 - 10:53the fundamental laws governing consciousness,
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10:53 - 10:55the laws that connect consciousness
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10:55 - 10:58to other fundamentals: space, time, mass,
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10:58 - 11:01physical processes.
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11:01 - 11:03Physicists sometimes say
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11:03 - 11:06that we want fundamental laws so simple
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11:06 - 11:10that we could write them on the front of a t-shirt.
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11:10 - 11:11Well I think something like that is the situation
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11:11 - 11:13we're in with consciousness.
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11:13 - 11:16We want to find fundamental laws so simple
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11:16 - 11:18we could write them on the front of a t-shirt.
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11:18 - 11:20We don't know what those laws are yet,
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11:20 - 11:24but that's what we're after.
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11:24 - 11:26The second crazy idea
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11:26 - 11:29is that consciousness might be universal.
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11:29 - 11:33Every system might have some degree
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11:33 - 11:36of consciousness.
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11:36 - 11:39This view is sometimes called panpsychism:
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11:39 - 11:42pan for all, psych for mind,
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11:42 - 11:44every system is conscious,
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11:44 - 11:48not just humans, dogs, mice, flies,
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11:48 - 11:51but even Rob Knight's microbes,
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11:51 - 11:53elementary particles.
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11:53 - 11:56Even a photon has some degree of consciousness.
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11:56 - 11:59The idea is not that photons are intelligent
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11:59 - 12:01or thinking.
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12:01 - 12:02It's not that a photon
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12:02 - 12:03is wracked with angst
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12:03 - 12:07because it's thinking, "Aww, I'm always
buzzing around near the speed of light. -
12:07 - 12:10I never get to slow down and smell the roses."
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12:10 - 12:12No, not like that.
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12:12 - 12:15But the thought is maybe photons might have
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12:15 - 12:18some element of raw, subjective feeling,
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12:18 - 12:22some primitive precursor to consciousness.
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12:22 - 12:25This may sound a bit kooky to you.
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12:25 - 12:27I mean, why would anyone think such a crazy thing?
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12:27 - 12:31Some motivation comes from the first crazy idea,
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12:31 - 12:33that consciousness is fundamental.
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12:33 - 12:37If it's fundamental, like space and time and mass,
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12:37 - 12:40it's natural to suppose that it might be universal too,
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12:40 - 12:42the way they are.
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12:42 - 12:44It's also worth noting that although the idea
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12:44 - 12:46seems counterintuitive to us,
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12:46 - 12:49it's much less counterintuitive to people
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12:49 - 12:50from different cultures,
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12:50 - 12:52where the human mind is seen as much more
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12:52 - 12:55continuous with nature.
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12:55 - 12:59A deeper motivation comes from the idea that
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12:59 - 13:01perhaps the most simple and powerful way
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13:01 - 13:03to find fundamental laws connecting consciousness
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13:03 - 13:05to physical processing
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13:05 - 13:08is to link consciousness to information.
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13:08 - 13:10Wherever there's information processing,
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13:10 - 13:11there's consciousness.
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13:11 - 13:14Complex information processing, like in a human,
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13:14 - 13:15complex consciousness.
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13:15 - 13:17Simple information processing,
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13:17 - 13:19simple consciousness.
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13:19 - 13:22A really exciting thing is in recent years
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13:22 - 13:25a neuroscientist, Giulio Tononi,
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13:25 - 13:26has taken this kind of theory
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13:26 - 13:28and developed it rigorously
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13:28 - 13:30with a mathematical theory.
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13:30 - 13:32He has a mathematical measure
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13:32 - 13:33of information integration
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13:33 - 13:35which he calls phi,
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13:35 - 13:37measuring the amount of information
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13:37 - 13:38integrated in a system.
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13:38 - 13:41And he supposes that phi goes along
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13:41 - 13:42with consciousness.
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13:42 - 13:44So in a human brain,
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13:44 - 13:46incredibly large amount of information integration,
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13:46 - 13:48high degree of phi,
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13:48 - 13:50a whole lot of consciousness.
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13:50 - 13:53In a mouse, medium degree
of information integration, -
13:53 - 13:54still pretty significant,
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13:54 - 13:56pretty serious amount of consciousness.
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13:56 - 13:59But as you go down to worms,
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13:59 - 14:02microbes, particles,
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14:02 - 14:04the amount of phi falls off.
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14:04 - 14:06The amount of information integration falls off,
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14:06 - 14:08but it's still non-zero.
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14:08 - 14:10On Tononi's theory,
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14:10 - 14:12there's still going to be a non-zero degree
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14:12 - 14:14of consciousness.
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14:14 - 14:16In effect, he's proposing a fundamental law
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14:16 - 14:19of consciousness: high phi, high consciousness.
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14:19 - 14:22Now, I don't know if this theory is right,
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14:22 - 14:25but it's actually perhaps the leading theory right now
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14:25 - 14:27in the science of consciousness,
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14:27 - 14:29and it's been used to integrate a whole range
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14:29 - 14:31of scientific data,
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14:31 - 14:34and it does have a nice property
that it is in fact simple enough -
14:34 - 14:37you can write it on the front of a t-shirt.
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14:37 - 14:40Another final motivation is that
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14:40 - 14:42panpsychism might help us to integrate
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14:42 - 14:45consciousness into the physical world.
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14:45 - 14:48Physicists and philosophers have often observed
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14:48 - 14:51that physics is curiously abstract.
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14:51 - 14:53It describes the structure of reality
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14:53 - 14:55using a bunch of equations,
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14:55 - 14:58but it doesn't tell us about the reality
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14:58 - 14:59that underlies it.
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14:59 - 15:01As Stephen Hawking puts it,
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15:01 - 15:05what puts the fire into the equations?
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15:05 - 15:08Well, on the panpsychist view,
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15:08 - 15:11you can leave the equations of physics as they are,
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15:11 - 15:12but you can take them to be describing
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15:12 - 15:14the flux of consciousness.
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15:14 - 15:16That's what physics really is ultimately doing,
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15:16 - 15:18describing the flux of consciousness.
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15:18 - 15:20On this view, it's consciousness
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15:20 - 15:24that puts the fire into the equations.
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15:24 - 15:26On that view, consciousness doesn't dangle
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15:26 - 15:27outside the physical world
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15:27 - 15:29as some kind of extra.
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15:29 - 15:32It's there right at its heart.
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15:32 - 15:35This view, I think, the panpsychist view,
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15:35 - 15:38has the potential to transfigure our relationship
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15:38 - 15:40to nature,
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15:40 - 15:42and it may have some pretty serious social
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15:42 - 15:46and ethical consequences.
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15:46 - 15:48Some of these may be counterintuitive.
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15:48 - 15:51I used to think I shouldn't eat anything
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15:51 - 15:54which is conscious,
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15:54 - 15:56so therefore I should be vegetarian.
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15:56 - 15:59Now, if you're a panpsychist and you take that view,
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15:59 - 16:02you're going to go very hungry.
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16:02 - 16:03So I think when you think about it,
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16:03 - 16:05this tends to transfigure your views,
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16:05 - 16:07whereas what matters for ethical purposes
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16:07 - 16:08and moral considerations,
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16:08 - 16:12not so much the fact of consciousness,
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16:12 - 16:16but the degree and the complexity of consciousness.
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16:16 - 16:17It's also natural to ask about consciousness
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16:17 - 16:20in other systems, like computers.
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16:20 - 16:22What about the artificially intelligent system
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16:22 - 16:26in the movie "Her," Samantha?
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16:26 - 16:27Is she conscious?
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16:27 - 16:29Well, if you take the informational,
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16:29 - 16:30panpsychist view,
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16:30 - 16:33she certainly has complicated information processing
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16:33 - 16:35and integration,
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16:35 - 16:37so the answer is very likely yes, she is conscious.
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16:37 - 16:40If that's right, it raises pretty serious
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16:40 - 16:43ethical issues about both the ethics
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16:43 - 16:46of developing intelligent computer systems
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16:46 - 16:49and the ethics of turning them off.
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16:49 - 16:51Finally, you might ask about the consciousness
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16:51 - 16:53of whole groups,
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16:53 - 16:55the planet.
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16:55 - 16:58Does Canada have its own consciousness?
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16:58 - 17:00Or at a more local level,
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17:00 - 17:01does an integrated group
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17:01 - 17:04like the audience at a TED conference,
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17:04 - 17:07are we right now having a
collective TED consciousness, -
17:07 - 17:09an inner movie
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17:09 - 17:11for this collective TED group
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17:11 - 17:13which is distinct from the inner movies
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17:13 - 17:14of each of our parts?
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17:14 - 17:16I don't know the answer to that question,
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17:16 - 17:18but I think it's at least one
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17:18 - 17:20worth taking seriously.
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17:20 - 17:22Okay, so this panpsychist vision,
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17:22 - 17:24it is a radical one,
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17:24 - 17:26and I don't know that it's correct.
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17:26 - 17:28I'm actually more confident about
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17:28 - 17:30the first crazy idea,
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17:30 - 17:32that consciousness is fundamental,
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17:32 - 17:34than about the second one,
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17:34 - 17:36that it's universal.
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17:36 - 17:38I mean, the view raises any number of questions,
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17:38 - 17:40has any number of challenges,
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17:40 - 17:41like how do those little bits
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17:41 - 17:43of consciousness add up
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17:43 - 17:45to the kind of complex consciousness
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17:45 - 17:47we know and love.
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17:47 - 17:49If we can answer those questions,
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17:49 - 17:50then I think we're going to be well on our way
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17:50 - 17:54to a serious theory of consciousness.
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17:54 - 17:57If not, well, this is the hardest problem perhaps
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17:57 - 17:59in science and philosophy.
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17:59 - 18:02We can't expect to solve it overnight.
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18:02 - 18:06But I do think we're going to figure it out eventually.
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18:06 - 18:09Understanding consciousness is a real key, I think,
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18:09 - 18:11both to understanding the universe
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18:11 - 18:14and to understanding ourselves.
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18:14 - 18:17It may just take the right crazy idea.
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18:17 - 18:19Thank you.
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18:19 - 18:20(Applause)
- Title:
- How do you explain consciousness?
- Speaker:
- David Chalmers
- Description:
-
Our consciousness is a fundamental aspect of our existence, says philosopher David Chalmers: “There’s nothing we know about more directly…. but at the same time it’s the most mysterious phenomenon in the universe.” He shares some ways to think about the movie playing in our heads.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TEDTalks
- Duration:
- 18:37
Morton Bast edited English subtitles for How do you explain consciousness? | ||
Morton Bast approved English subtitles for How do you explain consciousness? | ||
Morton Bast edited English subtitles for How do you explain consciousness? | ||
Morton Bast edited English subtitles for How do you explain consciousness? | ||
Morton Bast edited English subtitles for How do you explain consciousness? | ||
Madeleine Aronson accepted English subtitles for How do you explain consciousness? | ||
Madeleine Aronson edited English subtitles for How do you explain consciousness? | ||
Madeleine Aronson edited English subtitles for How do you explain consciousness? |