BROOKS: This is a double-headed
We're going to start off with a debate. Then we're
going - maybe it's a triple-headed event. We're going to start off
with a debate, then we're going to have a break for pizza and
soda - pizza lover here - outside, and then we're going to come back
for a lecture.
The event that this is around is the 70th anniversary of a paper
Alan Turing, "On Computable Numbers," published in 1936,
which one can legitimately, I think - I think one can legitimately
think of that paper as the foundation of computer science. It
included the invention of the Turing - what we now call the
Machine. And Turing went on to have lots of contributions to our
field, we at the Computer Science and Artificial Intelligence
Lab. In 1948, he had a paper titled, "Intelligent Machinery,"
which I think is really the foundation of artificial
So in honor of that 70th anniversary, we have a workshop going
on in the next couple days and this even tonight. This event is
sponsored by the Templeton Foundation. Charles Harper of the
Templeton Foundation is here, and so is Mary Ann Meyers and some
other people sponsoring this event. And Charles, I have to ask
you one question - A or B? You have to say. You have to choose.
This is going to choose who goes first, but I'm not telling you
who A or B is.
BROOKS: OK. So we're going to start this debate between
Ray Kurzweil and David Gelernter.
And it turns out that Ray is going
to go first. Thanks, Charles. So I'm first going to introduce
Ray and David. I will point out that after we finish and after
the break, we're going to come back at 6:15, and Jack Copeland,
who's down here, will then give a lecture on Turing's life.
Jack has been - runs the Alanturing.net, the archives in New
Zealand of Alan Turing, and he's got a wealth of material and
new material that's being declassified over time that he'll be
talking about some of Alan Turing's contributions.
But the debate that we're about to have is really about the AI
side of Alan Turing and the limits that we can expect or that we
might be afraid of or might be celebrating of whether we can
build super-intelligent machines, or are we limited to building
just super-intelligent zombies. We're pretty sure we can build
programs with intelligence, but will they just be zombies that
don't have the real oomph of us humans? Will it be possible or
desirable for us to build conscious, volitional, and perhaps
even spiritual machines?
So we're going to have a debate. Ray is going to speak for five
minutes and then David is going to speak for five
minutes - opening remarks. Then Ray will speak for ten minutes,
David for ten minutes - that's a total of 30 minutes, and I'm
going to time them. And then we're going to have a 15-minute
interplay between the two of them.
They get to use as much time
as they can get from the other one during that. And then we're
going to open up to some questions from the audience. But I do
ask that when we have the questions, the questions shouldn't be
for you to enter the debate. It would be better if you can come
up with some question which you think they can argue about,
because that's what we're here to see.
Ray Kurzweil has been a well-known name since his - in
artificial intelligence since his appearance on Steve Allen's
show in 1965, where he played a piano piece that a computer he
had built had composed.
Ray has gone on to -
KURZWEIL: I was three years old.
BROOKS: He was three years old, yes.
Ray has gone on to build
the Kurzweil synthesizers that many musicians use, the Kurzweil
reading machines, and many other inventions that have gone out
there and are in everyday use. He's got prizes and medals up the
He won the Lemelson Prize from MIT, he won the National
Medal of Technology, presented by President Clinton in 1999. And
Ray has written a number of books that have been - come out and
been very strong sellers on all sorts of questions about our
future and the future of robot kind.
David Gelernter is a professor at Yale University, professor of
computer science, but he's sort of a strange professor of
computer science, in the sense that he writes essays for Weekly
Standard, Time, Wall Street Journal, Washington Post, Los
Angeles Times, and many other sorts of places. And I see a few
of my colleagues here, and I'm glad they don't write columns for
all those places.
His research interests include AI,
philosophy of mind, parallel distributed systems, visualization,
and information management. And you can read all about them with
Google if you want to get more details. Both very distinguished
people, and I hope we have some interesting things to hear from
them. So we'll start with Ray.
And five minutes, Ray.
KURZWEIL: OK. Well, thanks, Rodney. You're very good at getting
a turnout. That went quickly. [laughter]
So there's a tie-in
with my tie, which this was given to me by Intel. It's a
photomicrograph of the Pentium, which I think symbolizes the
progress we've made since Turing's relay-based computer Ultra
that broke the Nazi Enigma code and enabled Britain to win the
Battle of Britain. But we've come a long way since then.
And in terms of this 70th anniversary, the course I enjoyed the
most here at MIT, when I was here in the late '60s, was 6.253 - I
don't remember all the numbers, and numbers are important here
- but that was theoretical models of computation, and it was
about that paper and about the Turing Machine and what it could
compute and computable functions and the busy beaver function,
which is non-computable, and what computers can do, and really
established computation as a sub-field of mathematics and,
arguably, mathematics as a sub-field of computation.
So in terms of the debate topic, I thought it was interesting
that there's an assumption in the title that we will build
super-intelligent machines, we'll build super-intelligent machines
that are conscious or not conscious. And it brings up the issue
of consciousness, and I want to focus on that for a moment,
because I think we can define consciousness in two ways.
We can define apparent
consciousness, which is an entity that appears to be
conscious - and I believe, in fact, you have to be apparently
conscious to pass the Turing test, which means you really need a
command of human emotion. Because if you're just very good at
doing mathematical theorems and making stock market investments
and so on, you're not going to pass the Turing test. And in
fact, we have machines that do a pretty good job with those
Mastering human emotion and human
language is really key to the Turing test, which has held up as
our exemplary assessment of whether or not a non-biological
intelligence has achieved human levels of intelligence.
And that will require a machine to master human emotion, which
in my view is really the cutting edge of human intelligence.
That's the most intelligent thing we do. Being funny, expressing
a loving sentiment - these are very complex behaviors. And we have
characters in video games that can try to do these things, but
they're not very convincing.
They don't have the complex, subtle
cues that we associate with those emotions. They don't really
have emotional intelligence. But emotional intelligence is not
some sideshow to human intelligence. It's really the cutting
edge. And as we build machines that can interact with us better
and really master human intelligence, that's going to be the
frontier. And in the ten minutes, I'll try to make the case that
we will achieve that. I think that's more of a 45-minute
argument, but I'll try to summarize my views on that.
I will say that the community, AI community and myself, have
gotten closer in our assessments of when that will be feasible.
There was a conference on my 1999 book, Spiritual Machines, at
Stanford, and there were AI experts. And the consensus then - my
feeling then was we would see it in 2029.
The consensus in the AI community
was, oh, it's going to - it's very complicated, it's going to take
hundreds of years, if we can ever do it. I gave a presentation - I
think you were there, Rodney, as well, at AI50, on the 50th
anniversary of the Dartmouth Conference that gave AI its name in
1956. And we had these instant polling devices, and they asked
ten different ways when a machine would pass the Turing
test - when will we know enough about the brain, when will we have
sophisticated enough software, when will a computer actually
pass the Turing test.
They got the same answer - it was
basically the same question, and they got the same answer. And
of course it was a bell curve, but the consensus was 50 years,
which, at least if you think logarithmically, as I do, that's
not that different from 25 years.
So I haven't changed my position, but the AI community is
getting closer to my view. And I'll try to explain why I think
that's the case. It's because of the exponential power of growth
in information technology, which will affect hardware, but also
will affect our understanding of the human brain, which is at
least one source of getting the software of intelligence.
The other definition of consciousness is subjectivity.
Consciousness is a synonym for subjectivity and really having
subjective experience, not just an entity that appears to have
subjective experience. And fundamentally - and I'll try to make
this point more fully in my ten-minute presentation - that's not a
There's no consciousness detector we
can imagine creating, that you'd slide an entity in - green light
goes on, OK, this one's conscious, no, this one's not
conscious - that doesn't have some philosophical assumptions built
So John Searle would make sure that
it's squirting human neurotransmitters -
BROOKS: Time's up.
KURZWEIL: OK. And Dan Dennett would make sure it's
self-reflexive. But we'll return to this.
GELERNTER: Let's see.
First, I'd like to say thanks for inviting
me. My guess is that the position I'm representing - the anti-cognitivist
position, broadly speaking - is not the overwhelming favorite at
this particular site. But I appreciate your willingness to
listen to unpopular opinions, and I'll try to make the most of
it by being as unpopular as I can. [Laughter]
First, it seems to me we won't even be able to build
super-intelligent zombies unless we attack the problem right, and
I'm not sure we're doing that. I'm pretty sure we're not. We
need to understand, it seems to me, in model thought as a whole
the cognitive continuum.
Not merely one or a discrete handful
of cognitive styles, the mind supports a continuum or spectrum
of thought styles reaching from focused analytical thought at
one extreme, associated with alertness or wide-awakeness, toward
steadily less-focused thought, in which our tendency to
free-associate increases. Finally, at the other extreme, that
tendency overwhelms everything else and we fall asleep.
So the spectrum reaches from focused analysis to unfocused
continuous free association and the edge of sleep. As we move
down-spectrum towards free association, naturally our tendency
to think analogically increases. As we move down-spectrum,
emotion becomes more important. I have to strongly agree with
Ray on the importance of emotion.
We speak of being coldly logical on
the one hand, but dreaming on the other is an emotional
experience. Is it possible to simulate the cognitive continuum
in software? I don't see why not. But only if we try.
Will we ever be able to build a conscious machine? Maybe, but
building one out of software seems to me virtually impossible.
First, of course, we have to say what conscious means. For my
purpose, consciousness means a subjectivity. And Ray's - and
consciousness means the presence of mental states that are
strictly private, with no visible functions or consequences.
A conscious entity can call up some
thought or memory merely to feel happy, to enjoy the memory, be
inspired or soothed or angered by the thought, get a rush of
adrenaline from the thought. And the outside world needn't see
any evidence of all that this act of thought or remembering is
Now, the reason I believe consciousness will never be built out
of software is that where software is executing, by definition
we can separate out, peel off a portable layer that can run in a
logically identical way on any computing platform - for example,
on a human mind. I know what it's like to be a computer
executing software, because I can execute that separable,
portable set of instructions just as an electronic digital
computer can and with the same logical effect.
If you believe that you can build
consciousness out of software, you believe that when you execute
the right sort of program, a new node of consciousness gets
created. But I can imagine executing any program without ever
causing a new node of consciousness to leap into being. Here I
am evaluating expressions, loops, and conditionals.
I can see this kind of activity
producing powerful unconscious intelligence, but I can't see it
creating a new node of consciousness. I don't even see where
that new node would be - floating in the air someplace, I guess.
And of course, there's no logical difference between my
executing the program and the computer's doing it. Notice that
this is not true of the brain. I do not know what it's like to
be a brain whose neurons are firing, because there is no
separable, portable layer that I can slip into when we're
dealing with the brain.
The mind cannot be ported to any
other platform or even to another instance of the same platform.
I know what it's like to be an active computer in a certain
abstract sense. I don't know what it's like to be an active
brain, and I can't make those same statements about the brain's
creating or not creating a new node of consciousness.
Sometimes people describe spirituality - to move finally to the
last topic - as a feeling of oneness with the universe or a
universal flow through the mind, a particular mode of thought
and style of thought. In principle, you could get a computer to
do that. But people who strike me as spiritual describe
spirituality as a physical need or want. My soul thirsteth for
God, for the living God, as the Book of Psalm says.
Can we build a robot with a physical
need for a non-physical thing? Maybe, but don't count on it. And
Is it desirable to build intelligent, conscious computers,
finally? I think it's desirable to learn as much as we can about
every part of the human being, but assembling a complete
conscious artificial human is a different project.
easily reach a state someday where we prefer the company of a
robot from Wal-Mart to our next door neighbors or roommates or
whatever, but it's sad that in a world where we tend to view
such a large proportion of our fellow human beings as useless,
we're so hot to build new ones. [laughter]
In a Western world that no longer cares to have children at the
replacement rate, we can't wait to make artificial humans.
Believe it or not, if we want more complete, fully functional
people, we could have them right now, all natural ones.
me afterwards, and I'll let you know how it's done. [laughter]
BROOKS: OK, great.
GELERNTER: Thank you.
KURZWEIL: You heard glimpses in David's presentation of both of
these concepts of consciousness, and we can debate them both. I
think principally he was talking about a form of performance
that incorporates emotional intelligence.
Because emotional intelligence, even
though it seems private and we assume that there is someone
actually home there experiencing the emotions that are
apparently the case, we can't really tell that when we look at
someone else. In fact, all that we can discuss scientifically is
objective observation, and science is really a synonym for
objectivity, and consciousness is a synonym for subjectivity,
and there is an inherent gulf between them.
So some people feel that actual consciousness doesn't exist,
since it's not a scientific concept, it's just an illusion, and
we shouldn't waste time talking about it. That's not fully
satisfactory, in my view, because our whole moral and ethical
and legal system is based on consciousness. If you cause
suffering to some other conscious entity, that's the basis of
our legal code and ethical values.
Some people describe some
magical or mystical property to consciousness. There were some
elements in David's remarks, say, in terms of talking about a
new node of consciousness and how that would suddenly emerge
My view is it's an emergent property of a complex system. It's
not dependent on substrate. But that is not a scientific view,
because there's really no way to talk about or to measure the
subjective experience of another entity. We assume that each
other are conscious. It's a share human assumption.
But that assumption breaks down when
we go out of shared human experience. The whole debate about
animal rights has to do with are these entities actually
conscious. Some people feel that animals are just machines in
the old-fashioned sense of that term, not - there's nobody really
home. Some people feel that animals are conscious. I feel that
my cat's conscious. Other people don't agree. They probably
haven't met my cat, but - (laughter)
But then the other view is apparent consciousness, an entity
that appears to be conscious, and that will require emotional
intelligence. There are several reasons why I feel that we will
achieve that in a machine, and that has to do with the
acceleration of information technology - and this is something
I've studied for several decades.
And information technology, not just
computation, but in all fields, is basically doubling every year
in price, performance, capacity, and bandwidth. We certainly can
see that in computation, but we can also see that in other
areas, like the resolution of brain-scanning in 3D volume is
doubling every year, the amount of data gathering on the brain
is doubling every year.
And we're showing that we can
actually turn this data into working models and simulations of
brain regions. There's about 20 regions of the brain that have
already been modeled and simulated.
And I've actually had a debate with Tomaso Poggio as to whether
this is useful, because he kept saying, well, OK, we'll learn
how the visual cortex works, but that's really not going to be
useful in creating artificial vision systems. And I said, well,
when we got these early transformations of the auditory cortex,
that actually did help us in speech recognition. It was not
intuitive, we didn't expect it, but when we plugged it into the
front-end transformations of speech recognition, we got a big
jump in performance.
They haven't done that yet in visual
modeling of the visual cortex. And I saw him recently - in fact,
at AI50 - and he said, you know, you were right about that,
because now they're actually getting models, these early models
of how the visual cortex works, and that that has been helpful
in artificial vision systems.
I make the case in chapter four of my book that we will have
models and simulations of all several hundred regions of the
human brain within 20 years. And you have to keep in mind that
the progress is exponential. So it's very seductive. It looks
like nothing is happening. People dismissed the genome project.
Now we think it's a mainstream
project, but halfway through the project, only 1% of the project
had been done, but the amount of genetic data doubled smoothly
every year and the project was done on time. If you can factor
in this exponential pace of progress, I believe we will have
models and simulations of these different brain regions - IBM is
already modeling a significant slice of the cerebral cortex.
And that will give us the templates
of intelligence, it will expand the AI toolkit, and it'll also
give us new insights into ourselves. And we'll be able to create
machines that have more facile emotional intelligence and that
really do have the subtle cues of emotional intelligence, and
that will be necessary to passing the Turing test.
But that still doesn't - that still begets the key question as to
whether or not those entities just appear to be conscious and
feeling emotion or whether they really have emotional subjective
David, I think, was giving a
sophisticated version of John Searle's Chinese room argument,
where - I don't have time to explain the whole argument, but for
those of you familiar with it, you've got a guy that's just
following some rules on a piece of paper and he's answering
questions in Chinese, and John says, well, isn't it ridiculous
to think that that system is actually conscious?
Or he has a mechanical typewriter
which types out answers in Chinese, but it's following complex
rules. The premise seems absurd that that system could actually
be - have true understanding and be conscious when it's just
following a simple set of rules on a piece of paper.
Of course, the sleight of hand in that argument is that these
set of rules would be immensely complex, and the whole premise
is unrealistic that such a simple system could, in fact,
realistically answer unanticipated questions in Chinese or any
language. Because basically what the man is doing in the Chinese
room, in John Searle's argument, is passing a Turing test. And
that entity would have to be very complex. And in that
complexity is a key emergent property.
So David says, well, it seems
ridiculous to think that software could be conscious or even - and
I'm not sure if he's - which flavor of consciousness he's using
there, the true subjectivity or just apparent consciousness, but
in either case it seems absurd that a little software program
could display that kind of complexity and self-emergent
But that's because you're thinking of software as you know it
today, if in fact you have a massively parallel system, as the
brain is, with 100 trillion internal connections, all of which
are computing simultaneously, and which in fact we can model
those internal connections and neurons quite realistically in
some cases today. We're still in the early part of that process.
But even John Searle agrees that a
neuron is basically a machine and can be modeled and simulated,
so why can't we do that with massively parallel system with 100
trillion-fold parallelism? And if that seems ridiculous, that is
ridiculous today, but it's not ridiculous with the kind of
technology we'll have with 30 more doublings of price,
performance, capacity, and bandwidth of information technology,
the kind of technology we'll have around 2030.
These massively parallel systems with the complexity of the
human brain, which is a moderate level of complexity, because
the design of the human brain is in the genome and the genome
has 800 million bytes, but that's uncompressed, has massive
redundancies - ALU's repeated 300,000 times.
If you apply loss that's compression
of the genome, you can reduce it to 30-50 million bytes, which
is not simple, but it's a level of complexity we can manage.
BROOKS: Ray, the logarithm of your remaining time is one.
KURZWEIL: So the - we'll be able to achieve that level of
We are making exponential progress in reverse
engineering the brain. We'll have systems that have the
suppleness of human intelligence. This will not be conventional
software as we understand it today.
There is a difference in the
(inaudible) field of technology when it achieves that level of
parallelism and that level of complexity, and I think we'll
achieve that if you consider these exponential progressions. And
it still doesn't penetrate the ultimate mystery of how
consciousness can emerge, true subjectivity.
We assume that each other are
conscious, but that assumption breaks down in the case of
animals, and we'll have a vigorous debate when we have these
machines. But I'll make one point. We will - I'll make a
prediction that we will come to believe these machines, because
they'll be very clever and they'll get mad at us if we don't
believe them, and we won't want that to happen.
So thank you.
BROOKS: OK. David?
GELERNTER: Well, thank you for those very eloquent remarks. And
I want to say, first of all, many points were raised.
premise of John Searle's Chinese room and of the thought
experiment which is related, that I outlined, is certainly
unrealistic. Granted, the premise is unrealistic. That's why we
have thought experiments. If the premise were not unrealistic,
if it were easy to run in a lab, we wouldn't need to have a
Now, the fact remains that when we conduct a thought experiment,
any thought experiment needs to be evaluated carefully. The fact
that we can imagine something doesn't mean that what we imagine
is the case. We need to know whether our thought experiment is
based on experience. I would say the thought experiment of
imagining that you're executing the instructions that constitute
a program or that realize a virtual machine is founded on
experience, because we've all had the experience of executing
algorithms by hand.
It isn't any - and there's no exotic
ingredient in executing instructions. I may be wrong. I don't
know for sure what would happen if I executed a truly enormous
program that went on for billions of pages. But I don't have any
reason for believing that consciousness would emerge. It seems
to me a completely arbitrary claim. It might be true. Anything
might be true. But I don't see why you make the claim. I don't
see what makes it plausible.
You mentioned massive parallelism, but massive parallelism,
after all, adds absolutely zero in terms of expressivity. You
could have a billion processors going, or ten billion or ten
trillion or 1081, and all those processors could be simulated on
a single jalopy PC. I could run all those processes
asynchronously on one processor, as you know, and what I get
from parallelism is performance, obviously, and a certain amount
of cleanliness and modularity when I write the program, but I
certainly don't get anything in terms of expressivity that I
didn't have anyway.
You mentioned consciousness, which is the key issue here. And
you pointed out consciousness is subjective. I'm only aware of
mine, you're only aware of yours, granted. You say that
consciousness is an emergent property of a complex system.
Granted, of course, the brain is obviously a complex system and
consciousness is clearly an emergent property.
Nobody would claim that one neuron
tweezed out of the brain was conscious. So yes, it is an
emergent property. The business about animals and people denying
animal consciousness, I haven't really heard that since the 18th
century, but who knows, maybe there are still Cartesians out
there - raise your hands.
But in the final analysis, although it's true that consciousness
is irreducibly subjective, you can't possibly claim to
understand the human mind if you don't understand consciousness.
It's true that I can't see yours and you can't see mine. It
doesn't change the fact that I know I'm conscious and you know
that you are. And I'm not going to believe that you understand
the human mind unless you can explain to me what consciousness
is, how it's created and how it got there. Now, that doesn't
mean that you can't do a lot of useful things without
being - creating consciousness.
You certainly can. If your ultimate
goal is utilitarian, forget about consciousness. But if your
goals are philosophical and scientific and you want to
understand how the mind really operates, then you must be able
to tell me how consciousness works, or you don't have a theory
of the human mind.
One element that I think you left out in your discussion of the
thought experiment and the fact that, granted, we're able to
build more and more complex systems and they are more and more
powerful, and we're able to build more and more accurate and
effective simulations of parts of the brain and indeed of other
parts of the body - because keep in mind that when we allow the
importance of emotion and thinking, it's clear that you don't
just think with your brain, you think with your body.
When you feel an emotion, when you
have an emotion, the body acts as a resonator or a sounding
board or an amplifier, and you need to understand how the body
works, as well as the brain does, if you're going to understand
emotion. But granted, we're getting - we're able to build more
complex and more and more effective simulators.
What isn't clear is the role of the brain's chemical structure.
The role of the brain stuff itself, of course, is a point that
Searle harps on, but it goes back to a paper by Paul Ziff in the
late 1950s, and many people have remarked on this point. We
don't have the right to dismiss out of hand the role of the
actual chemical makeup of the brain in creating the emergent
property of consciousness. We don't know whether it can be
created using any other substance.
Maybe it can't and maybe it can.
It's an empirical question.
One is reminded of the famous search that went on for so many
centuries for a substitute source of the pigment ultramarine.
Ultramarine, a tremendously important pigment for any painter.
You get it from lapis lazuli, and there are not very many
sources of lapis lazuli. It's very expensive, and it's a big
production number to get it and grind it down, turn it into
ultramarine. So ultramarine paint used to be as expensive as
People wanted to know, where else
can I get ultramarine? And they went to the scientific
community, and the scientific community said, we don't know.
There's no law that says there is some other place to get
ultramarine from lapis lazuli, but we'll try. And at a certain
point in the late 19th century, a team of French chemists did
succeed in producing a fake ultramarine pigment which was indeed
much cheaper than lapis lazuli. And the art world rejoiced.
The moral of the story? If you can do it, great, but you have no
basis for insisting on an a priori assumption that you can do
it. I don't know whether there is a way to achieve consciousness
in any way other than living organisms achieve it. If you think
there is, you've got to show me. I have no reason for accepting
that a priori.
And I think I'm finished.
BROOKS: I can't believe it. Everyone stopped - Ray, I think
up there, and we'll - now we'll go back and forth in terms of,
Ray, maybe you want to answer that.
KURZWEIL: So I'm struggling as I listen to your remarks, David,
to really tell what you mean by consciousness.
I've tried to
distinguish these two different ways of looking at it - the
objective view, which is usually what people lapse into when
they talk about consciousness. They talk about some neurological
property, or they talk about self-reflection, an entity that can
create models of its own intelligence and behavior and model
itself, or what-if experiments in its mind or have imagination,
thinking about itself and transforming models of itself and this
kind of self-reflection.
That is consciousness. Or maybe it
has to do with mirror neurons and that we can empathize - that is
to say, understand the conscious or the emotions of somebody
But that's all objective performance. And these - our emotional
intelligence, our ability to be funny or be sad or express a
loving sentiment, those are things that the brain does. And I'd
make the case that we are making progress, exponential progress
in understanding the human brain and different regions, and
modeling them in mathematical terms and then simulating them and
testing those simulations.
And the precision of those
simulations is gearing up. We can argue about the timeframe. I
think, though, within a quarter century or so, we will have
detailed models that - and simulations that can then do the same
things that the brain does apparently. And we won't be able to
really tell them apart.
That is what the Turing test is all about, that this machine
will pass the Turing test. But that is an objective test. We
could argue about the rules. Mitch Kapor and I argued for three
months about the rules. Turing wasn't very specific about them.
But it is a objective test and it's an objective property.
I'm not sure if you're talking about that or talking about the
actual sense one has of feeling, your apparent feelings, the
subjective sense of consciousness.
And so you talk about -
GELERNTER: (inaudible), could I answer that question?
BROOKS: Yeah, let (inaudible).
GELERNTER: You say there are two kinds of consciousness, and I
think you're right.
I think most people, when they talk about
consciousness, think of something that's objectively visible. As
I said, for my purposes, I want consciousness to mean mental
states, mental states - specifically a mental state that has no
KURZWEIL: But that's still -
GELERNTER: You know that you are capable of feeling or being
You know you're capable of thinking of something good
that makes you feel good, of thinking of something bad that
makes you depressed, or thinking of something outrageous that
makes you angry. You know you're capable of mental states that
are your property alone. As you say, there's
objective - absolutely -
KURZWEIL: But these mental states do have -
GELERNTER: That's what I mean by consciousness.
KURZWEIL: But these mental states still have objective
neurological correlates. And in fact, we now have means of where
we can begin to look inside the brain with increasing
resolution - strike doubling in 3D volume every year - to actually
see what's going on in the brain.
So sitting there quietly, thinking
happy thoughts and making myself happy, you can - there are
actually things going on inside the brain, we're able to see
them. And so now this supposedly subjective mental state is, in
fact, becoming an objective behavior. Not -
GELERNTER: Can I comment on that? I think you're - I think the
idea that you're arguing with Descartes is a straw man approach.
I don't think anybody argues anymore that the mind is a result
of mind stuff, some intangible substance that has no relation to
the brain. By arguing that consciousness is objective - I'm
agreeing with you that consciousness is objective - I'm certainly
not denying that it's created by physical mechanisms. I'm not
claiming there's some magical or transcendental metaphysical
But that doesn't change the fact
that in terms of the way you understand it and perceive it, your
experiences of it is subjective. That was your term, and I'm
agreeing with you. And that doesn't change the fact that it is
created by the brain.
Clearly, we're reaching better and better understandings of the
brain and of everything else. You've said that a few times, and
I certainly don't disagree. The fact that we're getting better
and better doesn't mean that necessarily we're going to reach
any arbitrary goal. It depends on our methods.
It depends if we understand the
problem the right way. It depends if we're taking the right
route. It seems to me that consciousness is necessary. Unless we
understand consciousness as this objective phenomenon that we're
all aware of, our brain simulators haven't really told us
anything fundamental about the human mind.
Haven't told us what I want to know.
KURZWEIL: I think our brain simulators are going to have to work
not just the level of the Turing test, but at the level of
measuring the objective neurological correlates of these
supposedly internal mental states.
And there's some information
processing going on when we daydream and we think happy thoughts
or sad thoughts or worry about something.
There's same kinds of things going
on as when we do more visibly intelligent tasks. We're, in fact,
more and more able to penetrate that by seeing what's going on
and modeling these different regions of the brain, including,
say, the spindle cells and the mirror neurons, which are
involved with things like empathy and emotion - which are uniquely
human, although a few other animals have some of them - and really
beginning to model this.
We're at an early stage, and it's easy to ridicule the
primitiveness of today's technology, which will also always
appear primitive compared to what will be feasible, given the
But these internal mental states
are, in fact, objective behaviors, because we will need to
expand our definition of objective behavior to the kinds of
things that we can see when we look inside the brain.
GELERNTER: If I could comment on that?
If your tests are telling
us that they are unable to distinguish that the same thing
creates, on the one hand, a mental state of sharply-focused, in
which I'm able to concentrate on a problem without my mind
drifting and solving it - there's no way to distinguish that
mental state from a mental state in which my mind is wandering,
I am unable to focus or concentrate on what I'm doing, and then
I start dreaming.
In fact, cognitive psychologists
have found out that we start dreaming and then we fall asleep.
If your tests or your simulators are unable to distinguish
between the mental state of dreaming or continuous free
association on the one hand and focused logical analytic
problem-solving on the other, then I think you're just telling
us that your tests have failed, because we know that these
states are different and we want to know why they're different.
It doesn't do any good to say, well, they're caused in the same
We need to explain the difference
that we can observe.
BROOKS: Can I ask a question which I think gets at what this
disagreement is? Then I'll ask you two different questions.
question for David is, what would it take to convince you so
that you would accept that you could build a conscious computer
built on digital substrate? And Ray, what would it take to
convince you that digital stuff isn't good enough, we need some
other chemicals or something else that David talked about?
KURZWEIL: To answer it myself, I wouldn't get too hung up on
digital, because, in fact, the brain is not digital.
neurotransmitters are kind of a digitally-controlled analog
phenomena. But when we figure out the salient - the important
thing is to figure out what is salient and how information is
modeled and what these different regions are actually doing to
The actual neurons are very complex. There's lots of things
going on, but we find out in the - one region of the auditory
cortex is basically conducting a certain type of algorithm, the
information is represented perhaps by the location of certain
neurotransmitters in relation to another, whereas in another
case it has to do with the production of some unique
There's different ways in which the
information is represented. And these are chemical processes,
but we can model really anything like that at whatever level of
specificity is needed digitally. We know that.
We can model it analog -
BROOKS: OK, so you didn't answer the question. Can you then
answer the question? (laughter)
GELERNTER: I will continue in exactly the same spirit, by not
answering the question. I wish I could answer the question. It
is a very good question and a deep question.
Given the fact that mental states
that are purely private are also purely subjective, how can we
tell when they are present? And the fact is, just as you don't
know how to produce them, I don't know how to tell whether they
are there. It's a research question, it's a philosophical
It's - we know how to understand particular technologies. That is,
we say I've created consciousness and I've done it by running
software on a digital computer. I can think about that and say I
don't buy that, I don't believe there's consciousness there. If
you wheel in some other technology, my only stratagem is to try
and understand that new technology. I need to understand what
you're doing, I need to understand what moves you're making,
because unfortunately I don't know of any general test.
The only test that one reads about
or hears about philosophically is relevant similarity - that is,
we assume that our fellow human beings are conscious, because we
can see they're people like us. We assume that if I had mental
states, other similar creatures have mental states. And we make
that same assumption about animals. And the more similar to us
they seem, the more we assume their mental states are like ours.
How are we going to handle creatures who are - or things or
entities, objects, that are radically unlike us and are not
organic? It's a hard question and an interesting question.
I'd like to see more work done on
KURZWEIL: In some ways, they'll be more like us than animals,
because animals are not perfect models of humans either
medically or mentally.
Whereas as we really
reverse-engineer what's going on, the salient processes, and
learn what's important in the different regions of the brain and
recreate those properties and abilities to transform information
similar ways, and then get an entity that in fact acts very
human-like and a lot more human-like than an animal, for
example, can pass a Turing test, which involves mastery of
language which animals basically don't have, for the most part,
they will be closer to humans than animals are.
If we really model - take an extreme case. I don't think this is
necessary to model neuron by neuron and neurotransmitter by
neurotransmitter, but one could in theory do that. And we have,
in fact, do have simulations of neurons that are highly detailed
already, of one neuron or a cluster of three or four of them. So
why not extend that to 100 billion neurons? It's theoretically
possible, and it's a different substrate, but it's really doing
the same things.
And it's closer to humans than
BROOKS: So while David responds, if people who want to ask
questions can come to the two microphones. Go ahead.
GELERNTER: When you say act very human-like, this is a key
You have to keep in mind that the Turing test is rejected
by many people, and has been from the very beginning, as a
superficial test of performance, a test that fails to tell us
anything about mental states, fails to tell us the things that
we really most want to know.
So when you say something acts very
human-like, that's exactly what we don't do when we attribute
the presence of consciousness on the basis of relevant
When I see somebody, even if he isn't acting human-like at all,
if he's fast asleep, even if he's out cold, I don't need to see
him do anything, I don't need to have him answer any fancy
questions on the Turing test. I can see he's a creature like I
am, and I therefore attribute to him a mind and believe he's
capable of mental states.
On the other hand, the Turing test,
which is a test of performance rather than states of being, has
been - has certainly failed to convince people who are interested
in what you would call the subjective kind of consciousness.
KURZWEIL: Well, I think now we're -
GELERNTER: That doesn't tell me anything about -
KURZWEIL: Well, now I think we're getting somewhere, because I
The Turing test is an objective test. And we can
argue about making it super-rigorous and so forth, but - and if an
entity passed that test, the super-rigorous one, it is really
convincingly human. It's convincingly funny and sad, and we
really - is really displaying those emotions in a way that we
cannot distinguish from human beings.
But you're right - I mean, this gets
back to a point I made initially. That doesn't prove that that
entity is conscious, and we don't absolutely know that people
are conscious. I think we will come to accept them as conscious.
That's a prediction I can make. But fundamentally, this is the
underlying ontological question.
There is actually a role for philosophy, because it's not
fundamentally a scientific question. If you reject the Turing
test or any variant of it, then we're just left with this
philosophical issue. My own philosophical take is if an entity
seems to be conscious, I would accept its consciousness.
But that's a philosophical and not a
BROOKS: So I think we'll take the first question. And remember,
not a monologue, something to provoke discussion.
M: Yeah, no problem. Let's see. What if everything is
conscious and connected, and it's just a matter of us learning
how to communicate and connect with it?
KURZWEIL: That's a good point, because we can communicate with
other humans, to some extent - although history is full of
examples where we dehumanize a certain portion of the population
and don't really accept their conscious experience - and we have
trouble communicating with animals, so that really underlies the
whole animal rights - what's it like to be a giant squid?
Their behavior seems very
intelligent, but it's also very alien and we don't - there's no
way we can even have the terminology to express that, because
it's not experiences that are human. And that is part of the
deep mystery of consciousness and gets at the subjective aspects
But as we do really begin to model our own brain and then extend
that to other species, as we're doing with the genome - we're now
trying to reverse-engineer the genome in other species, and
we'll do the same thing ultimately with the brain - that will give
us more insight.
We can translate into our own human
terms the kinds of mental states as we can see them manifest as
we really understand how to model other brains.
GELERNTER: If we think we are communicating with a
software-powered robot, we're kidding ourselves, because we're
using words in a fundamentally different way.
To use an example
that Turing himself discusses, we could ask the computer or the
robot, do you like strawberries, and the computer could lie and
say yes or it could, in a sense, tell the truth and say no.
But the more fundamental issue is
that not only does it not like strawberries, it doesn't like
anything. It's never had the experience of liking, it's never
had the experience of eating. It doesn't know what a strawberry
is or any other kind of berry or any other kind of fruit or any
other kind of food item. It doesn't know what liking is, it
doesn't know what hating is.
It's using words in a purely
syntactic way with no meanings behind them.
KURZWEIL: This is now the Searlean argument, and John Searle's
argument can be really rephrased to prove that the human being
has no understanding and no consciousness, because each neuron
is just a machine. Instead of just shuffling symbols, it's just
shuffling chemicals. And obviously, just shuffling chemicals
around is no different than shuffling symbols around.
And if shuffling chemicals and
symbols around doesn't really lead to real understanding or
consciousness, then why isn't that true for a collection of 100
neurons, which are all just little machines, or 100 billion?
GELERNTER: There's a fundamental distinction, which is
software. Software is the distinction. I can't download your
brain onto the computer up there -
KURZWEIL: Well, that's just a limitation of my brain, because we
don't have - we don't have quick downloading ports.
GELERNTER: You need somebody else's brain in the audience?
KURZWEIL: No, that's something that biology left out. We're just
not going to leave that out of our non-biological base.
GELERNTER: It turns out to be an important point. It's
the fundamental issue -
KURZWEIL: It's a limitation, not -
GELERNTER: I think there's a very big difference whether I can
take this computer and upload it to a million other computers or
to machines that are nothing like this digital computer, to a
Turing machine, to an organic computer, to an optical computer.
I can upload it to a class full of freshmen, I can upload it to
all sorts of things.
But your mind is yours and will
never be downloaded (multiple conversations; inaudible) -
KURZWEIL: That's just because we left -
GELERNTER: It's stuck to your brain.
KURZWEIL: We left out the -
GELERNTER: And I think that's a thought-provoking fact. I
don't think you can just dismiss it as an -
KURZWEIL: You're posing that as a -
GELERNTER: - envir - a developmental accident. Maybe it
is, but -
KURZWEIL: You're posing that as a benefit and advantage
of biological intelligence, that we don't have these quick
downloading ports to access information -
GELERNTER: Not an advantage. It's just a fact.
KURZWEIL: But that's not an advantage. If we added quick
downloading ports, which we will add to our non-biological brain
emulations, that's just an added feature. We could leave it out.
But we put it in there, that doesn't deprive it of any
capability that it would otherwise have.
GELERNTER: You think you could upload your mind to somebody with
a different body, with a different environment, who had a
different set of experiences, who had a different set of books,
feels things in a different way, has a different set of likes,
responds in a different kind of way, and get an exact copy of
I think that's a na´ve idea. I don't
think there's any way to upload your mind anywhere else and that
lets you upload your entire being, including your body.
KURZWEIL: Well, it's hard to upload to another person who
already has a brain and a body that's - it's like trying to upload
to a machine that's incompatible. But ultimately we will be able
to gather enough data on a specific brain and simulate that,
including our body and our environmental influences.
BROOKS: Next question.
M: Thanks. If we eventually develop a machine which
appears intelligent, and let's say given appropriate body so
that it can answer meaningful questions about how does a
strawberry taste or something like that or whether it likes
strawberries, if we are wondering if this machine is actually
experiencing consciousness the same way that we do, why not just
They'll presumably have no reason to
lie if you haven't specifically gone out of your way to program
KURZWEIL: Well, that doesn't tell us anything, because we can
ask it today. You can ask a character in a video game and it
will say, well, I'm really angry or I'm sad or whatever. And we
don't believe it, because it doesn't - it's not very convincing
yet. It doesn't - because it doesn't have the subtle cues and
it's not as complex and not a realistic emulation of -
M: Well, if we built 1000 of them, let's say -
GELERNTER: I strongly agree with (inaudible) -
M: - presumably they wouldn't all agree to lie ahead of
time. Somebody - one of them might tell us the truth if the answer
BROOKS: We'll finish that question (multiple
conversations; inaudible) -
GELERNTER: I strongly agree. Keep in mind that the whole basis
of the Turing test is lying. The computer is instructed to lie
and pass itself off as a human being. Turing assumes that
everything it says will be a lie. He doesn't talk about the real
deep meaning of lying, or he doesn't care about that, and that's
fine, that's not his topic.
But he'd - it's certainly not the case
that the computer is in any sense telling the truth. It's
telling you something about its performance, not something about
facts or reality or the way it's made or what its mental life is
KURZWEIL: John Searle, by the way, thinks that a snail
could be conscious if it had this magic property, which we don't
understand it, that causes consciousness. And when we figure it
out, we may discover that snails have it. That's his view. So I
do think that -
GELERNTER: Do you think it's inherently implausible that we
should need a certain chemical to produce a certain result? Do
you think chemical structure is irrelevant?
KURZWEIL: No, but we can simulate chemical interactions. We just
simulated the other day something that people said will never be
able to be simulated, which is protein folding. And we can now
take an arbitrary amino acid sequence and actually simulate and
watch it fold up, and it's an accurate simulation (multiple
GELERNTER: You understand it, but you don't get any amino acids
out. As Searle points out, if you want to talk Searlean, you can
simulate photosynthesis and no photosynthesis takes place. You
can simulate a rainstorm, nobody gets wet. There's an important
distinction. Certainly you're going to understand the process,
but you're not going to produce the result -
KURZWEIL: Well, if you simulate creativity, you'll - if you
simulate creativity, you'll get real ideas out.
BROOKS: Next - sure.
M: So up until this point, there seems to have been a lot of
discussion just about a fully - just software, just a human or
whatnot. But I'm kind of curious your thoughts towards more of a
gray area, if it's possible. That is, if we in some way augment
the brain with some sort of electronic component, or somebody
has some sort of operation to add something to them.
I don't think it's been done yet
today, but just is it possible to have fully - what you would
consider to be a fully conscious human take part of the brain
out, say, replace it with something to do a similar function,
and then have obviously the person still survive. Is that person
Is it (inaudible)?
KURZWEIL: Absolutely. And we've done things like that, which
But I think - in fact, that is the key application
or one key application of this technology. We're not just going
to create these super-intelligent machines to compete with us
from over the horizon. We're going to enhance our own
intelligence, which we do now with the machines in our
pockets - and when we put them in our bodies and brains, we'll
enhance our bodies and brains with them.
But we are applying this for medical problems. You can get a
pea-sized computer placed in your brain or placed at biological
neurons (inaudible) Parkinson's disease. And in fact, the latest
generation now allows you to download new software to your
neural implant from outside the patient, and that does replace
the function of the corpus of biological neurons.
And now you've got biological
neurons in the vicinity getting signals from this computer where
they used to get signals from the biological neurons, and this
hybrid works quite well. And there's about a dozen neural
implants, some of which are getting more and more sophisticated,
in various stages of development.
So right now we're trying to bring back "normal" function,
although normal human function is in fact a wide range. But
ultimately we will be sending blood cell-sized robots to the
bloodstream non-invasively to interact with our biological
neurons. And that sounds very fantastic.
I point out there's already four
major conferences on blood cell-sized devices that can produce
therapeutic functions in animals and - we don't have time to
discuss all that, but we will -
BROOKS: Let's hear David's response.
GELERNTER: When you talk about technological interventions that
could change the brain, it's a remarkable - it's a fascinating
topic, and it can do a lot of good. And one of the really famous
instances of that is the frontal lobotomy, an operation invented
in the 1950s or maybe the last 1940s.
Made people feel a lot better, but
somehow it didn't really catch on, because it bent their
personality out of shape. So the bottom line is not everything
that we do, not every technological intervention that affects
your mental state is necessarily going to be good.
Now, it is a great thing to be able to come up with something
that cures a disease, makes somebody feel better. We need to do
as much of that as we can, and we are. But we - it's impossible to
be too careful when you fool around with consciousness. You may
make a mistake that you will regret.
And lobotomy cases are undoable.
BROOKS: I'm afraid this is going to be the last question.
M: How close do the brain simulation people know they are to the
right architecture, and how do they know it? You made the
assertion that you don't need to simulate the neurons in detail,
and that the IBM people are simulating a slice of neocortex and
And I think that is good, but do
they have a theory that says this architecture good, this
architecture not good enough?
How do they measure it?
KURZWEIL: Well, say, in the case of the simulation of a dozen
regions of the auditory cortex done on the West Coast, they've
applied sophisticated psychoacoustic tests to the simulation and
they get very similar results as applying the same test to human
There's a simulation of the
cerebellum where they apply skill formation tests. It doesn't
prove that these are perfect simulations, but it does show it's
on the right track. And the overall performance of these regions
appears to be doing the kinds of things that we can measure,
that the biological versions do. And the scale and
sophistication and resolution of these simulations is scaling
The IBM one on the cerebral cortex is actually going to do it
neuron by neuron and ultimately at the chemical level, which I
don't believe is actually necessary when we - ultimately, to
actually create those functions, when we learn the salient
algorithms, we can basically implement them using our computer
science methods more efficiently.
But that's a very useful project to
really understand how the brain works.
GELERNTER: I'm all in favor of neural simulations. I
think one should keep in mind that we don't think just with our
brains, we think with our brains and our bodies. Ultimately,
we'll have to simulate both.
And we also have to keep in mind
that unless our simulators can tell us not only what the
input/output behavior of the human mind is, but how it
understands and how it produces consciousness - unless it can
tell us where consciousness comes from, it's not enough to say
it's an emergent phenomenon. Granted, but how? How does it work?
Unless those questions are answered, we don't understand the
We're kidding ourselves if we think
BROOKS: So with that, I think I'd like to thank both Ray and