
Tell YC: Answers from John McCarthy - mgummelt
John McCarthy came to my class at Stanford on Wednesday May 7.  Here is a VERY rough transcript of the informal interview.  It comes from my notes that I was taking/my memory.  These are definititely not verbatim quotes from McCarthy.<p>-----Professor's Interview Questions-----<p>Q. Can Computers Think?<p>A. Thinking isn't one thing.  It has many aspects.  For example, computers have the ability to remember information and the ability to play games.  Some aspects of thinking, we have not succeeded in.  A notable examples is the analysis of situations.  A computer cannot break a situation into parts, analyze the parts separately, and then combine the parts to come to a conclusion.  A specific manifestation of this is the game "Go".  This type of thinking is necessary in "Go", where it is not in Chess.  This is why the best computers are as good as people in Chess, but the best computers are much worse than people in "Go".<p>Q. Is there anything in principle that would prevent a computer from thinking as a human would?<p>A. No<p>Q. Can computers know?<p>A. This is largely a question of definition.  If a camera looked at a table, we could say it "knows" that there are four containers of liquid on the table (which was true).<p>Q. Is there any definition of "know" in which computers cannot succeed?<p>A.  Well, I suppose the biblical sense.<p>Q. Ha, well, what makes you think that?<p>A.  They don't satisfy the necessary axioms (laughter)<p>Q. OK, can a computer have free will?<p>A. In my paper over free will, I defined "simple deterministic free will," which a computer can have.  In fact, modern chess playing computers have this.  However, this is not always true for displays of artificial intelligence.  Consider two optimal tic-tac-toe playing programs.  The first evalutes future situations in order to choose the optimal solution.  The other simply looks at the state of the board, for which there are only 3^9 possibilities, and picks a move from a lookup table.  The first program exhibits simple deterministic free will, where the second program does not.  A chess program cannot have a lookup table because the state is too complex.  Thus quantitative considerations are important.  Philosophers would have you believe that they are not. That a chess problem and a tic tac toe problem are equivalent.  I believe quantitative considerations are important.<p>Q. Simple deterministic free will does not require that a computer know that it has free will.  How would a computer know that it has free will?<p>A.  Well, computers are good at understanding theories.  My theory of simple deterministic free will is a theory.  You could teach it this theory.<p>Q. Are there some senses of free will that aren't simple deterministic?<p>A.  (I didn't catch the first part of his response) Some believe that free will is acheived through random aspects of quantum mechanics.  This is particularly attractive to people who don't understand quantum mechanics.<p>Q. Can computers achieve consciousness?<p>A. Human consciousness starts with being aware of basic things such as hunger.  Advanced states of consciousness are simply more elaborate forms of these basic awarenesses.  We have a surprisingly limited ability to examine our own state.  We ought to remember what we've had for breakfast for the past 30 days, but we can't.  Short answer -&#62; yes, machines can have consciousness.<p>-----Student Questions-----<p>Q. Why would we want to give computer's emotions?<p>A.  Human emotion involves the state of the blood, and this is inherited from our animal ancestors.  Giving a computer this kind of emotion, or "state of the blood", would not be to our advantage.<p>Q. (Something that led him to talk about his new language Elephant)<p>A. Elephant was meant to come out in 2005, but 2005 has come and gone and the language isn't ready yet.  It is a new way to talk to computers.  I/O is done through speech acts.  (He said something about the programming language dealing in obligations and promises, and I'm not sure what that means)<p>My Q: While we're on the same topic of computer languages, would you consider Lisp more of an invention or a discovery?<p>A.  If I hadn't come up with it, someone else would have.  Pure Lisp was a discovery, everything that has been done with it since has been an invention.  It started out as a formula for conditional expressions (if c then a else b).  The logical structure followed from that.  I got the idea from Newell and Simon.  They came out with a language called IPL in 1956.  I heard about it, and thought it was a fascinating idea.  I saw the language and thought it was horrible.<p>Q. What is the future of AI?<p>A.  Well, I'm really hoping the next great idea will appear soon.  Yoav (our professor) is probably too old (laughter).  I will tell you this: If you go to my web page and look at me when I did most of my initial work, I wasn't much older than you <i>looks expectantly around the room...</i><p>--------<p>Overall, it was an amazingly interesting talk.  I'm not sure how well I captured that here.  I wish I could have asked him more technical questions, but we were out of time.  The best part, and probably one of the highlights of my freshman year at Stanford, was after class.  My professor asked me if I had any experience editing wikis, and I said yes.  He then asked me if I would mind helping McCarthy edit his wikipedia page and I said "sure", and I'm pretty sure my voice squeaked a little.  A few minutes later, I was behind a computer, and John McCarthy was over my shoulder telling me what to add to HIS wikipedia page.  I tried to stay and talk afterwards, but was shooed away.
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jorgeortiz85

       Q. Can computers know?
    
       A. This is largely a question of definition. If a camera
       looked at a table, we could say it "knows" that there are
       four containers of liquid on the table (which was true).
    

This is definitely a very old school approach to AI and one that I don't find
very convincing. If a computer with a camera is looking at a table with four
containers of liquid, to say that it "knows" "there are four containers of
liquid on the table" presupposes that it "knows" what a "container" is, what a
"liquid" is, and what a "table" is, and that it can recognize and point out
each of these things in its 640x480 grid of RGB values and describe the
essential properties of a container, a liquid, and a table. Even that
presupposes that things like "container", "liquid" and "table" have "essential
properties".

(That's an interesting question: what makes a table a table? Not all tables
are made out of the same material or have the same color. Not all tables have
four legs (or legs at all!) and not all have a flat surface. Not all tables
are the same height or width or are used for the same purposes. What, then,
makes some particular table "a table"?)

We don't say that a camera "knows" there's three glasses of water on the table
when it takes a picture any more than we say a newborn baby "knows" when he
looks at a chessboard that Kasparov has a mate in three.

I guess I shouldn't take McCarthy's comments at a freshman seminar as
representative of his most thorough theories on AI, but I found that one
answer particularly naive.

~~~
mgummelt
I don't think this example represented his definition of "knowing". He was
using it to show that there are very basic definitions of the word.

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simplegeek
_If I hadn't come up with it, someone else would have. Pure Lisp was a
discovery, everything that has been done with it since has been an invention_

For me , this pretty much sums it up--thank you for posting ;)

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JesseAldridge
Elephant sounds interesting. More info here: <http://www-
formal.stanford.edu/jmc/elephant/elephant.html>

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prakash
Cool! Such experiences are awesome.

 _A. If I hadn't come up with it, someone else would have. Pure Lisp was a
discovery, everything that has been done with it since has been an invention._

This brought back thoughts about Gladwell's recent essay which was posted
here.

~~~
aston
Although Gladwell would argue that Lisp, too, was as much an invention as
anything done with it afterwards, insofar as the person who invented, say,
CLOS was simply discovering it (in McCarthy's terms) before someone else did.

~~~
herdrick
Probably a continuum from discovery to invention. I don't know CLOS, but it
sounds like mostly an invention.

Aston - email me at info@reatlas.com please.

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mechanical_fish
_Some believe that free will is acheived through random aspects of quantum
mechanics. This is particularly attractive to people who don't understand
quantum mechanics._

This man is now my personal hero.

Suddenly I understand why so many bright people were drawn to work with
McCarthy. :)

~~~
jderick
Can someone explain this? It seems the connection between quantum mechanics
and free will are being dismissed out of hand. However, this seems like a deep
question that probably has no simple answer. Is this just a 'religious' issue?
Or is there a simple explanation why there is no connection here..

~~~
mechanical_fish
The "simple" explanation is that lots of people think that quantum mechanics
is nondeterministic. And it isn't. If you know the quantum state of a system
at time X you can figure out what it will be at any time after that.

People get confused because it's easy to look at a quantum mechanics problem
from the wrong angle and see nondeterminism. We're really well trained in
intuitive mechanics ("an electron is like a tiny tennis ball, and tennis balls
are always either _here_ or _there_ , right?") so at first glance quantum
mechanics seems wacky and random: the electron might be here, or it might be
there, with _equal probability_ , and we can't tell which! Whereupon your head
explodes. Seriously: The discoverers of quantum exploded in horror, and they
started ranting about that crazy cat in the box, or "God playing dice".
(Colorful but misleading metaphors. One reason that Bohr and Einstein's early
confusion persists today is that they were just so darned _eloquent_.)

In fact, God does not play dice: God sees _all the outcomes of the dice roll
at the same time_ and doesn't understand why we think it's a game, and not a
static work of art.

People also think that nondeterminism is somehow an important ingredient in
whatever it is we mean by "free will". This doesn't make much sense to me. If
you want it to not make sense to you as well, read Daniel Dennett's _Freedom
Evolves_. You might want to budget more than a couple hours for that book,
though.

~~~
sfk
God does not play dice? Are you saying that you can figure out radioactive
decay?

From [<http://www.fourmilab.ch/hotbits/how3.html>]

"But hidden variables aren't the way our universe works—it really is random,
right down to its gnarly, subatomic roots. In 1964, the physicist John Bell
proved a theorem which showed hidden variable (little clock in the nucleus)
theories inconsistent with the foundations of quantum mechanics. In 1982,
Alain Aspect and his colleagues performed an experiment to test Bell's
theoretical result and discovered, to nobody's surprise, that the predictions
of quantum theory were correct: the randomness is inherent—not due to
limitations in our ability to make measurements. So, given a Cæsium-137
nucleus, there is no way whatsoever to predict when it will decay. If we have
a large number of them, we can be confident half will decay in 30.17 years;
but if we have a single atom, pinned in a laser ion trap, all we can say is
that is there's even odds it will decay sometime in the next 30.17 years, but
as to precisely when we're fundamentally quantum clueless. The only way to
know when a given Cæsium-137 nucleus decays is after the fact—by detecting the
ejecta. A Cæsium-137 nucleus which has “beat the reaper” by surviving a
century, during which time only one in a thousand of its litter-mates haven't
taken the plunge and turned into Barium, has precisely the same chance of
surviving another hundred years as a newly-minted Cæsium-137, fresh from the
reactor core."

~~~
hugh
Go read the overcomingbias essay on the Many-Worlds interpretation posted
above. (Or is it below?)

The short answer is that in the many-worlds interpretation, this too is a
deterministic process. The total wavefunction of the whole system (atom +
observer) evolves deterministically. What isn't deterministic is "your"
subjective view of it, but "you" only view a vanishingly small slice of
reality.

Sorry, that's the best three-sentence explanation I can come up with right
now, and I admit it's only a shade better than "trust me, I'm a physicist".
But trust me, I'm a physicist.

------
gruseom
_I tried to stay and talk afterwards, but was shooed away._

That's too bad. I always noticed the distinction between professors who
welcomed interaction with students and those who shooed students away.
Stanford has a lot of the latter. (Update: my assumption is that this is truer
in general of top-tier schools than average ones, probably because smart, keen
students stand out more at average schools and so get more attention. Of
course, average schools have fewer smart, keen teachers too. But if you
connect with the right one, the experience can be life-changing.)

~~~
mgummelt
No no no. I shouldn't have said I was shooed away. I was actually invited to
stay for a bit after class and talk, but I made a mistake. My professor asked
me if I had a class to go to, and I told him that I did but I could skip it.
He told me I shouldn't skip my classes, so THEN I had to leave. Stanford
professors, even the nobel prize winners, are extremely open to talk to
undergrads after class or during office hours.

~~~
bootload
_"... I was actually invited to stay for a bit after class and talk, but I
made a mistake. My professor asked me if I had a class to go to, and I told
him that I did but I could skip it. He told me I shouldn't skip my classes, so
THEN I had to leave. ..."_

Unfortunate. Next time stand your ground. You might not get another chance to
meet someone like McCarthy.

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sage_joch
"We ought to remember what we've had for breakfast for the past 30 days, but
we can't."

Bullshit - I've had Cocoa Puffs.

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radu_floricica
Good enough to drool over. But I'd really want to know what he thinks about
production software, not just the cute standard AI/consciousness questions.
Like how to make a better faster more fiable and more customizable ERP
workhorse.

~~~
byrneseyeview
If only we knew more about how Spinoza made those lenses.

~~~
radu_floricica
It's like asking Hawkins about black holes. These people have huge careers
that are not limited to what every digger knows about them. For one thing, his
most recent work - Elephant - is a lot more about production software then
about AI, and for another they must be pretty bored to answer the same "what
is consciousness" and "does light really disappear in a black hole" questions.

Also forgive me about wanting to be a better programmer, especially here on
hacker news. What was I thinking.

~~~
byrneseyeview
That is a fair point. But I think Hawkins can probably tell us more
interesting things about black holes than about, say, 101 tricks for quickly
simplifying a differential equation. If there's a question that nobody but
McCarthy could answer satisfactorily, McCarthy is the one to ask.

~~~
radu_floricica
That was the reason for my original post. I think McCarthy can tell us a lot
about production software too, probably a lot more then most. It's just nobody
asks him, and instead we get the same answers we can find in his last 10
interviews.

I wouldn't mind AI questions too, if only they were a bit more original.

------
jsmcgd
Had anyone else just assumed McCarthy was dead? Sorry John.

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jorgeortiz85
Out of curiosity, what class was this?

~~~
jorgeortiz85
nevermind, you mention the professor and you're a freshman, so i assume it's
cs21n.

~~~
mgummelt
Yea, CS21N. It's the least technical CS class you can probably take.

------
dzorz
Mac users who actually want to be able to read the text: press
ctrl+alt+command+8.

------
Monkeyget
More exciting than P=NP : Does Turing Complete = Human Complete?

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rms
this should be on the front page

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volida
from your memory??

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markm
On an unrelated note, is anyone else having trouble reading this because of
the dark-gray on light-gray background?

~~~
kilowatt
Yes. Unfortunately Hacker News looks like it was designed by hackers :[

But that's like the 10th time hard-to-read-text has happened to me today, and
it gives me an idea.

On-the-fly, stored in the cloud site specific CSS customizations would be a
killer feature for a Firefox extension. Something that useful must already be
in Firebug ;) /goes to check

~~~
revorad
<https://addons.mozilla.org/en-US/firefox/addon/60>

------
lst
Humans have spontaneous thoughts, allowing us to build something in our mind
first, and then trying to build it concretely.

(So we can think to build computers, but computers can't think to build
humans...)

Neither animals nor computers will ever be able of that.

Although, I find his responses quite superficial sometimes.

~~~
byrneseyeview
"Spontaneous", huh? Does that mean it was truly random (e.g. that you're just
as likely to think up a coherent sentence in Farsi as in English) or that you
are not consciously aware of the process that leads to it? Either way, a
computer can handle it: it can operate on outputs for which the inputs or
processes are not known, or it can take some random inputs.

~~~
lst
With 'spontaneous' I mean: not caused by anything. All really new ideas are
spontaneous.

You find them (freshly created) inside yourself, but you can't tell where they
were coming from.

~~~
lst
(Sorry, but simply down-voting isn't 'good enough' here -- if you aren't able
to provide some convincing argument, you just _confirm_ my opinion.)

