As part of MIT course 6S099 on Artificial General Intelligence, I got a chance to sit down with Christoph Koch, who's 1 of the seminal figures in neurobiology, neuroscience, and generally in the study of consciousness.

He is the president, the chief scientific officer of the Allen Institute for Brain Science in Seattle.

From 1986 to 2013, he was a professor at Caltech.

He is Extremely well cited, over 100,000 citations.

His research, his writing, his ideas have had big impact on the scientific community and the general public in the way we think about consciousness, in the way we see ourselves as human beings.

He's the author of several books, The Quest for Consciousness and Your Biological Approach, and a more recent book, Consciousness, Confessions of a Romantic Reductionist.

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Okay, before we delve into the beautiful mysteries of consciousness, Let's zoom out a little bit and let me ask do you think there's intelligent life out there in the universe?

We have no evidence of it but I think the probabilities are overwhelming in favor of it.

Given universe where we have 10 to the 11 galaxies and each galaxy has between 10 to the 11, 10 to the 12 stars and we know most stars have 1 or more planets.

It still makes me feel special because I have experiences.

I feel the world, I experience the world.

And independent of whether there are other creatures out there, I still feel the world and I have access to this world in this very strange compelling way and that's the core of human existence.

Now you said human, do you think if those intelligent creatures are out there, do you think they experience their world?

they are evolved, if they are a product of natural evolution as they would have to be, they will also experience their own world.

So consciousness isn't just human, you're right, it's much wider.

It's probably, it may be spread across all of biology.

We have, the only thing that we have special is we can talk about it.

Of course not all people can talk about it.

Babies and little children can talk about it.

Patients who have who have a stroke in the left inferior frontal gyrus can talk about it.

But most normal adult people can talk about it and so we think that makes us special compared to let's say monkeys or dogs or cats or mice or all the other creatures that we share the planet with.

But all the evidence seems to suggest that they too experience the world and so it's overwhelmingly likely that other aliens that aliens would also experience their world.

Of course differently because they have a different sensorium, they have different sensors, they have a very different environment.

But the fact that I would strongly suppose that they also have experiences.

They feel pain and pleasure and see in some sort of spectrum and hear and have all the other senses.

Of course their language if they have 1 would be different so we might not be able to understand their poetry about the experiences that they have.

So in a talk, in a video, I've heard you mention Sapuzo, a Dachshund that you came up with, that you grew up with, was part of your family when you were young.

First of all, you're technically a Midwestern boy.

But after that, you traveled around a bit, hence a little bit of the accent.

You talked about Sopozo, the Dachshund, having these elements of humanness, of consciousness that you discovered.

So I just wanted to ask, can you look back in your childhood and remember when was the first time you realized you yourself, sort of from a third person perspective, are a conscious being.

This idea of stepping outside yourself and seeing there's something special going on here in my brain.

I can't really actually, it's a good question.

I'm not sure I recall a discrete moment I mean you take it for granted because that's the only world you know right the only world I know you know it's a world of seeing and hearing voices and touching and all the other things.

So it's only much later, at early in my undergraduate days when I became, when I enrolled in physics and in philosophy, that I really thought about it and thought, well, this is really fundamentally very, very mysterious.

And there's nothing really in physics right now that explains this transition from the physics of the brain to feelings.

So you can look at the foundational equation of quantum mechanics general relativity, you can look at the periodic table of the elements, you can look at the endless ATGC chat in our genes and nowhere is consciousness yet I wake up every morning to a world where I have experiences and so that's the heart of the ancient mind-body problem how do experiences get into the world.

Some people call it subjective feeling, some people call it phenomenology, some people call it qualia of the philosopher, but they all denote the same thing it feels like something in the famous word of the philosopher Thomas Nagel it feels like something to be a bat or to be you know an American or to be angry or to be sad or to be in love or to have pain.

And that is what experience is, any possible experience.

Could be as mundane as just sitting in a chair, could be as exalted as having a mystical moment in deep meditation.

Those are just different forms of experiences.

So if you were to sit down with maybe the next skip a couple generations of IBM Watson, something that won Jeopardy.

What is the gap I guess the question is between Watson that might be much smarter than you, than us, than all any human alive, but may not have experience.

That's occupied people for the last, certainly, last 50 years since we, you know, since the advent, the birth of computers.

That's a question Alan Turing tried to answer, and, of course, he did it in this indirect way by proposing a test, an operational test.

So, but that's not really, that's, you know, he tried to get at what does it mean for a person to think, and then he had this test, right, you lock him away, and then you have a communication with them, and then you try to guess after a while whether that is a person or whether it's a computer system.

There's no question that now or very soon, Alexa or Siri or Google Now will pass this test.

And you can game it, but ultimately, certainly in your generation, there will be machines that will speak with complete poise, that will remember everything you ever said, that will remember every email you ever had.

Like Samantha, remember in the movie, Her?

There's no question it's going to happen.

But of course, the key question is, does it feel like anything to be Samantha in the movie, Her?

And there, 1 has to very strongly think there are 2 different concepts here that we commingle.

There is a concept of intelligence, natural or artificial.

And there is a concept of consciousness, of experience, natural or artificial.

Now, historically, we associate consciousness with intelligence.

Because we live in a world, leaving aside computers, of natural selection, where we are surrounded by creatures, either our own kin that are less or more intelligent, or we go across species.

Some are more adapted to a particular environment, others are less adapted, whether it's a whale or dog or you go talk about a paramecium or a little worm, all right.

And we see the complexity of the nervous system goes from 1 cell to specialized cells to a worm that has 3 net that has 30% of its cells are nerve cells to creature like us or like a blue whale that has 100 billion even more nerve cells.

And so based on behavioral evidence and based on the underlying neuroscience, we believe that as these creatures become more complex, they are better adapted to their particular ecological niche and they become more conscious, partly because their brain grows and we believe consciousness, unlike the ancient, ancient people thought most, almost every culture thought that consciousness with intelligence has to do with your heart.

You say, honey, I love you with all my heart.

But what you should actually say is, you say, no, honey, I love you with all my lateral hypothalamus.

And for Valentine's Day, you should give your sweetheart a hypothalamic-shaped piece of chocolate and not a heart-shaped chocolate.

Anyway, so we still have this language, but now we believe it's a brain.

And so we see brains of different complexity, and we think, well, they have different levels of consciousness.

They're capable of different experiences.

But now we confront a world where we know, where we're beginning to engineer intelligence and it's radical unclear whether the intelligence we're engineering has anything to do with consciousness and whether it can experience anything.

Because fundamentally what's the difference?

Intelligence no matter exactly how you define it, sort of adaptation to new environments, being able to learn and quickly understand you know the setup of this and what's going on and who are the actors and what's gonna happen next that's all about function.

You can see folks that you can see this in several cases.

You can see it for instance in the case of the clinic.

When you're dealing with patients who are let's say had a stroke or had were in traffic accident etc.

Terry Schiavo you may have heard historically she was a person here in the 90s in Florida.

Then for the next 14 years, she was what's called in a vegetative state.

There are thousands of people in a vegetative state.

Occasionally, they open their eyes for 234568 hours, and then close their eyes.

But there's no way that you can establish a lawful relationship between what you say or the doctor says or the mom says and what the patient does.

So there isn't any behavior yet in some of these people there is still experience.

You can design and build brain machine interfaces where you can see they still experience something.

And of course, there are these cases of locked-in state.

There's this famous book called The Diving Bell and the Butterfly, where you had an editor, a French editor, he had a stroke in the brainstem, unable to move except his vertical eyes, eye movement.

He could just move his eyes up and down, and he dictated an entire book.

And some people even lose this at the end.

All the evidence seems to suggest that they're still in there.

In this case, you have no behavior, you have consciousness.

Second case is tonight, like all of us, you're going to go to sleep.

You will wake up inside your sleeping body, and you will have conscious experiences.

They are different from everyday experience.

You might fly, you might not be surprised that you're flying, you might meet a long dead pet childhood dog and you're not surprised that you're meeting them, you know, but you have conscious experience of love, of hate, you know, they can be very emotional.

Your body during this state, typically it's REM, state sends an active signal to your motor neurons to paralyze you, it's called atonia, right?

Because if you don't have that, like some patients, what do you do?

get, for example, REM behavioral disorder, which is bad juju to get.

So I recently had this, what some people call a mystical experience.

I went to Singapore and went into a flotation tank.

So this is a big tub filled with water that's body temperature and Epsom salt.

You strip completely naked, you lie inside of it, you close the lid.

So very quickly you become bodyless because you're floating and you're naked.

There's no photon, sightless, timeless because after a while, early on you actually hear your heart, but then you sort of adapt to that, and then the passage of time ceases.

And if you train yourself in a meditation not to think—early on, you think a lot.

You feel somewhat uncomfortable, or You think, well, I'm going to get bored.

But if you try not to think actively, you become mindless.

There you are, bodiless, timeless, soundless, sightless, mindless.

You're not remembering, you're not projecting, you're not planning, yet you are fully conscious.

What is the function of you being able to lay in this sensory-free deprivation tank and still have a conscious experience?

Obviously we didn't evolve with flotation tanks in our environment.

I mean, so biology is notoriously bad at asking why question, tele-anomical question.

Why don't we have 4 eyes, like some teachers or 3 eyes or something?

Well, no, there's probably a function to that, but we're not very good at answering those questions.

Science is very good about mechanistic questions.

We find a certain universe where there are positive and negative charges.

Quantum mechanics hold in our universe, it's very unclear why.

So teleonomical questions, why questions are difficult to answer.

Clearly there's some relationship between complexity, brain processing power, and consciousness.

But however, in these cases, in these 3 examples I gave, 1 is an everyday experience at night, the other 1 is a trauma, and third 1 is in principle, everybody can have these sort of mystical experiences.

You have a dissociation of function, of intelligence, from

Let me ask a question that's not a why question.

You're giving a talk later today on the Turing test for intelligence and consciousness, drawing lines between the 2.

So is there a scientific way to say there's consciousness present in this entity or not?

And to anticipate your answer, because there's a neurobiological answer.

So we can test a human brain but if you take a machine brain that you don't know tests for yet how would you even begin to approach a test if there's consciousness present in this thing?

So as you point out for humans, let's just stick with humans, there's now a test called the ZAP and ZIP.

It's a procedure where you ping the brain using transcranial magnetic stimulation.

You look at the electrical reverberations, essentially using EG, and then you can measure the complexity of this brain response.

And you can do this in awake people, in asleep, normal people.

You can do it in awake people and then anesthetize them.

And it has 100% accuracy that in all those cases, when you're clear, the patient or the person is either conscious or unconscious, the complexity is either high or low.

And then you can adopt these techniques to similar creatures like monkeys and dogs and mice that have very similar brains.

Now, of course, you point out that may not help you because we don't have a cortex.

And if I send a magnetic pulse into my iPhone or my computer, it's probably going to break something.

So what we need ultimately, we need a theory of consciousness.

Our intuition is, well, yeah, if somebody talks, they're conscious.

However, then there are all these children, babies, don't talk, right?

But we believe that babies also have conscious experiences, right?

And then there are all these patients I mentioned, and they don't talk.

When you dream, you can't talk because you're paralyzed.

So what we ultimately need, we can't just rely on our intuition.

We need a theory of conscience that tells us what is it about a piece of matter, What is it about a piece of highly excitable matter, like the brain or like a computer, that gives rise to conscious experience?

We all believe, none of us believe anymore in the old story, it's a soul, right?

That used to be the most common explanation that most people accept.

And still a lot of people today believe, well, there's God in doubt, Only us with a special thing that animals don't have.

Rene Descartes famously said, a dog, if you hit it with your carriage, may yelp, may cry, but it doesn't have this special thing.

Now we believe that isn't the case anymore.

So what is the difference between brains and these guys, silicon?

And in particular, once their behavior matches, so if you have Siri or Alexa in 20 years from now that she can talk just as good as any possible human, what grounds do you have to say she's not conscious?

In particular, if she says, of course she will.

You ask her how are you doing and she'll say, well, you know, they'll generate some way to.

1 is, so this relates to the problem, the very hard, why is consciousness a hard problem?

Only I have it, For only I know, I have direct experience of my own consciousness.

I don't have experience of your consciousness.

Now, I assume as a sort of a Bayesian person who believes in probability theory and all of that, you know, I can do an abduction to the best available facts.

I deduce your brain is very similar to mine.

If I put you in a scanner, your brain is roughly going to behave the same way as I do.

If I gave you this muesli and asked you, how does it taste?

You'd tell me things that I would also say, more or less.

So I infer based on all of that that you're conscious.

So there I really need a theory that tells me what is it about any system, this or this, that makes it conscious.

Yes, so the integrated information theory.

But let me first, maybe as an introduction for people who are not familiar, Descartes, can you, you talk a lot about panpsychism, can you describe what physicalism versus dualism, you mentioned the soul, What is the history of that idea?

Well no, the debate really out of which panpsychism can emerge of dualism versus physicalism.

Or do you not see panpsychism as fitting into that?

So panpsychism is a very ancient belief that's been around.

I mean, Plato and Aristotle talks about it.

Of course, in Buddhism, the idea is very prevalent, that, I mean, there are different versions of it.

1 version says everything is in soul, everything.

Rocks and stones and dogs and people and forests and iPhones, all of us are all, right?

Another version is that all biology, all creatures, small or large, from a single cell to a giant sequoia tree, feel like something.

That's 1 I think is somewhat more realistic.

It may well be possible that it feels like something to be a paramecium.

I think it's pretty likely it feels like something to be a bee or a mouse or a dog.

And you can, to some people, for example, Bertrand Russell, tried to advocate this idea, it's called Russellian monism, that panpsychism is really physics viewed from the inside.

So the idea is that physics is very good at describing relationship among objects, like charges or like gravity, right?

You know, it describes the relationship between curvature and mass distribution, okay?

Physics doesn't really describe the ultimate reality itself.

It's just relationship among, you know, quarks or all these other stuff.

It's sort of like a third person observer.

And consciousness is what physics feels from the inside.

So my conscious experience, it's the way the physics of my brain, particularly my cortex, feels from the inside.

And so if you are paramecium, you've got to remember, you say, paramecium, well, that's a pretty dumb creature.

But it has already a billion different molecules, probably 5,000 different proteins assembled in a highly, highly complex system that no single person, no computer system so far on this planet has ever managed to accurately simulate.

Yes, and it may well be that that little thing feels like a tiny bit.

Now it doesn't have a voice in the head like me, it doesn't have expectations, you know, it doesn't have all that complex things, but it may well feel like something.

Can we draw some lines and maybe try to understand the difference between life, intelligence, and consciousness.

If you have to define what is a living thing, what is a conscious thing, and what is an intelligent thing, Do those intermix for you or are they totally separate?

Okay, so A, that's a question that we don't have a full answer to.

A lot of the stuff we're talking about today is full of mysteries and fascinating ones, right?

Well, for example, you can go to Aristotle, who's probably the most important scientist and philosopher who's ever lived, certainly in Western culture.

He had this idea, it's called hylomorphism, it's quite popular these days, that there are different forms of soul.

The soul is really the form of something.

He says all biological creatures have a vegetative soul.

Today we think we understand something more that it's biochemistry and nonlinear thermodynamics.

Only animals and humans have also a sensitive soul or a petitive soul.

They can see, they can smell, and they have drives.

They want to reproduce, they want to eat, et cetera.

And then only humans have what he called a rational soul.

And that idea then made it into Christendom, and then the rational soul is the 1 that lives forever.

He wasn't really, I mean, different readings of Aristotle give different, whether did he believe that rational soul was immortal or not.

But then, of course, that made it into through Plato into Christianity, and then this soul became immortal and then became the connection to God.

Now, so you ask me, essentially, what is our modern conception of these 3, Aristotle would have called them, different forms?

Life, we think we know something about it, at least life on this planet, although we don't understand how it originated, but it's been difficult to rigorously pin down.

You see this in modern definitions of death.

It's in fact, right now there's a conference ongoing, again, that tries to define legally and medically what is death.

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Christof Koch: Consciousness | Lex Fridman Podcast #2