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发信人: eos (白杨), 信区: Science
标  题: 祖神回归式科学
发信站: 紫丁香 (Sun Sep 27 08:20:09 1998), 转信

【以下文字转载自 eos 的信箱】
【原文由 Wang 所发表】
发信人: physics (子曰:仨银行，必有偶师的说~), 信区: Science
标  题: 祖神回归式科学
发信站: BBS 水木清华站 (Thu Jan  8 15:28:08 1998) <b><font color="#00FF00">WWW-POST</font></b>

这是Feynman在加州理工一次毕业典礼上的讲话，后被收录于《爱开玩笑的科学家》中。
该文用十分幽默的方式讨论了科学家应有的道德。

Cargo Cult Science by Richard
Feynman

(Adapted from a Caltech commencement address given in 1974; HTML'ed
from the book ;Surely You're Joking, Mr. Feynman!)

During the Middle Ages there were all kinds of crazy ideas, such as that a
piece of rhinoceros horn
would increase potency. Then a method was discovered for separating the ideas
-- which was to try
one to see if it worked, and if it didn't work, to eliminate it. This method
became organized, of
course, into science. And it developed very well, so that we are now in the
scientific age. It is such a
scientific age, in fact, that we have difficulty in understanding how witch
doctors could ever have
existed, when nothing that they proposed ever really worked -- or very little
of it did.

But even today I meet lots of people who sooner or later get me into a
conversation about UFO's,
or astrology, or some form of mysticism, expanded consciousness, new types of
awareness, ESP,
and so forth. And I've concluded that it's not a scientific world.

Most people believe so many wonderful things that I decided to investigate
why they did. And what
has been referred to as my curiosity for investigation has landed me in a
difficulty where I found so
much junk that I'm overwhelmed. First I started out by investigating various
ideas of mysticism and
mystic experiences. I went into isolation tanks and got many hours of
hallucinations, so I know
something about that. Then I went to Esalen, which is a hotbed of this kind
of thought (it's a
wonderful place; you should go visit there). Then I became overwhelmed. I
didn't realize how
MUCH there was.

At Esalen there are some large baths fed by hot springs situated on a ledge
about thirty feet above
the ocean. One of my most pleasurable experiences has been to sit in one of
those baths and watch
the waves crashing onto the rocky slope below, to gaze into the clear blue
sky above, and to study a
beautiful nude as she quietly appears and settles into the bath with me.

One time I sat down in a bath where there was a beatiful girl sitting with a
guy who didn't seem to
know her. Right away I began thinking, "Gee! How am I gonna get started
talking to this beautiful
nude woman?"

I'm trying to figure out what to say, when the guy says to her, "I'm, uh,
studying massage. Could I
practice on you?"

"Sure", she says. They get out of the bath and she lies down on a massage
table nearby.

I think to myself, "What a nifty line! I can never think of anything like
that!" He starts to rub her big
toe. "I think I feel it", he says. "I feel a kind of dent -- is that the
pituitary?"

I blurt out, "You're a helluva long way from the pituitary, man!"

They looked at me, horrified -- I had blown my cover -- and said, "It's
reflexology!"

I quickly closed my eyes and appeared to be meditating.

That's just an example of the kind of things that overwhelm me. I also looked
into extrasensory
perception, and PSI phenomena, and the latest craze there was Uri Geller, a
man who is supposed
to be able to bend keys by rubbing them with his finger. So I went to his
hotel room, on his
invitation, to see a demonstration of both mindreading and bending keys. He
didn't do any
mindreading that succeeded; nobody can read my mind, I guess. And my boy held
a key and Geller
rubbed it, and nothing happened. Then he told us it works better under water,
and so you can
picture all of us standing in the bathroom with the water turned on and the
key under it, and him
rubbing the key with his finger. Nothing happened. So I was unable to
investigate that phenomenon.

But then I began to think, what else is there that we believe? (And I thought
then about the witch
doctors, and how easy it would have been to check on them by noticing that
nothing really worked.)
So I found things that even more people believe, such as that we have some
knowledge of how to
educate. There are big schools of reading methods and mathematics methods,
and so forth, but if
you notice, you'll see the reading scores keep going down -- or hardly going
up -- in spite of the fact
that we continually use these same people to improve the methods. There's a
witch doctor remedy
that doesn't work. It ought to be looked into; how do they know that their
method should work?
Another example is how to treat criminals. We obviously have made no progress
-- lots of theory,
but no progress -- in decreasing the amount of crime by the method that we
use to handle criminals.

Yet these things are said to be scientific. We study them. And I think
ordinary people with
commonsense ideas are intimidated by this pseudoscience. A teacher who has
some good idea of
how to teach her children to read is forced by the school system to do it
some other way -- or is
even fooled by the school system into thinking that her method is not
necessarily a good one. Or a
parent of bad boys, after disciplining them in one way or another, feels
guilty for the rest of her life
because she didn't do "the right thing", according to the experts.

So we really ought to look into theories that don't work, and science that
isn't science.

I think the educational and psychological studies I mentioned are examples of
what I would like to
call cargo cult science. In the South Seas there is a cargo cult of people.
During the war they saw
airplanes with lots of good materials, and they want the same thing to happen
now. So they've
arranged to make things like runways, to put fires along the sides of the
runways, to make a wooden
hut for a man to sit in, with two wooden pieces on his head to headphones and
bars of bamboo
sticking out like antennas -- he's the controller -- and they wait for the
airplanes to land. They're
doing everything right. The form is perfect. It looks exactly the way it
looked before. But it doesn't
work. No airplanes land. So I call these things cargo cult science, because
they follow all the
apparent precepts and forms of scientific investigation, but they're missing
something essential,
because the planes don't land.

Now it behooves me, of course, to tell you what they're missing. But it would
be just about as
difficult to explain to the South Sea islanders how they have to arrange
things so that they get some
wealth in their system. It is not something simple like telling them how to
improve the shapes of the
earphones. But there is one feature I notice that is generally missing in
cargo cult science. That is the
idea that we all hope you have learned in studying science in school -- we
never say explicitly what
this is, but just hope that you catch on by all the examples of scientific
investigation. It is interesting,
therefore, to bring it out now and speak of it explicitly. It's a kind of
scientific integrity, a principle of
scientific thought that corresponds to a kind of utter honesty -- a kind of
leaning over backwards.
For example, if you're doing an experiment, you should report everything that
you think might make
it invalid -- not only what you think is right about it: other causes that
could possibly explain your
results; and things you thought of that you've eliminated by some other
experiment, and how they
worked -- to make sure the other fellow can tell they have been eliminated.

Details that could throw doubt on your interpretation must be given, if you
know them. You must do
the best you can -- if you know anything at all wrong, or possibly wrong --
to explain it. If you make
a theory, for example, and advertise it, or put it out, then you must also
put down all the facts that
disagree with it, as well as those that agree with it. There is also a more
subtle problem. When you
have put a lot of ideas together to make an elaborate theory, you want to
make sure, when
explaining what it fits, that those things it fits are not just the things
that gave you the idea for the
theory; but that the finished theory makes something else come out right, in
addition.

In summary, the idea is to give all of the information to help others to
judge the value of your
contribution; not just the information that leads to judgement in one
particular direction or another.

The easiest way to explain this idea is to contrast it, for example, with
advertising. Last night I heard
that Wesson oil doesn't soak through food. Well, that's true. It's not
dishonest; but the thing I'm
talking about is not just a matter of not being dishonest; it's a matter of
scientific integrity, which is
another level. The fact that should be added to that advertising statement is
that no oils soak through
food, if operated at a certain temperature. If operated at another
temperature, they all will --
including Wesson oil. So it's the implication which has been conveyed, not
the fact, which is true,
and the difference is what we have to deal with.

We've learned from experience that the truth will come out. Other
experimenters will repeat your
experiment and find out whether you were wrong or right. Nature's phenomena
will agree or they'll
disagree with your theory. And, although you may gain some temporary fame and
excitement, you
will not gain a good reputation as a scientist if you haven't tried to be
very careful in this kind of
work. And it's this type of integrity, this kind of care not to fool
yourself, that is missing to a large
extent in much of the research in cargo cult science.

A great deal of their difficulty is, of course, the difficulty of the subject
and the inapplicability of the
scientific method to the subject. Nevertheless, it should be remarked that
this is not the only
difficulty. That's why the planes don't land -- but they don't land.

We have learned a lot from experience about how to handle some of the ways we
fool ourselves.
One example: Millikan measured the charge on an electron by an experiment
with falling oil drops,
and got an answer which we now know not to be quite right. It's a little bit
off because he had the
incorrect value for the viscosity of air. It's interesting to look at the
history of measurements of the
charge of an electron, after Millikan. If you plot them as a function of
time, you find that one is a little
bit bigger than Millikan's, and the next one's a little bit bigger than that,
and the next one's a little bit
bigger than that, until finally they settle down to a number which is higher.

Why didn't they discover the new number was higher right away? It's a thing
that scientists are
ashamed of -- this history -- because it's apparent that people did things
like this: when they got a
number that was too high above Millikan's, they thought something must be
wrong -- and they would
look for and find a reason why something might be wrong. When they got a
number close to
Millikan's value they didn't look so hard. And so they eliminated the numbers
that were too far off,
and did other things like that. We've learned those tricks nowadays, and now
we don't have that
kind of a disease.

But this long history of learning how to not fool ourselves -- of having
utter scientific integrity -- is,
I'm sorry to say, something that we haven't specifically included in any
particular course that I know
of. We just hope you've caught on by osmosis

The first principle is that you must not fool yourself -- and you are the
easiest person to fool. So you
have to be very careful about that. After you've not fooled yourself, it's
easy not to fool other
scientists. You just have to be honest in a conventional way after that.

I would like to add something that's not essential to the science, but
something I kind of believe,
which is that you should not fool the layman when you're talking as a
scientist. I am not trying to tell
you what to do about cheating on your wife, or fooling your girlfriend, or
something like that, when
you're not trying to be a scientist, but just trying to be an ordinary human
being. We'll leave those
problems up to you and your rabbi. I'm talking about a specific, extra type
of integrity that is not
lying, but bending over backwards to show how you're maybe wrong, that you
ought to have when
acting as a scientist. And this is our responsibility as scientists,
certainly to other scientists, and I think
to laymen.

For example, I was a little surprised when I was talking to a friend who was
going to go on the
radio. He does work on cosmology and astronomy, and he wondered how he would
explain what
the applications of his work were. "Well", I said, "there aren't any". He
said, "Yes, but then we won't
get support for more research of this kind". I think that's kind of
dishonest. If you're representing
yourself as a scientist, then you should explain to the layman what you're
doing -- and if they don't
support you under those circumstances, then that's their decision.

One example of the principle is this: If you've made up your mind to test a
theory, or you want to
explain some idea, you should always decide to publish it whichever way it
comes out. If we only
publish results of a certain kind, we can make the argument look good. We
must publish BOTH
kinds of results.

I say that's also important in giving certain types of government advice.
Supposing a senator asked
you for advice about whether drilling a hole should be done in his state; and
you decide it would be
better in some other state. If you don't publish such a result, it seems to
me you're not giving
scientific advice. You're being used. If your answer happens to come out in
the direction the
government or the politicians like, they can use it as an argument in their
favor; if it comes out the
other way, they don't publish at all. That's not giving scientific advice.

Other kinds of errors are more characteristic of poor science. When I was at
Cornell, I often talked
to the people in the psychology department. One of the students told me she
wanted to do an
experiment that went something like this -- it had been found by others that
under certain
circumstances, X, rats did something, A. She was curious as to whether, if
she changed the
circumstances to Y, they would still do A. So her proposal was to do the
experiment under
circumstances Y and see if they still did A.

I explained to her that it was necessary first to repeat in her laboratory
the experiment of the other
person -- to do it under condition X to see if she could also get result A,
and then change to Y and
see if A changed. Then she would know the the real difference was the thing
she thought she had
under control.

She was very delighted with this new idea, and went to her professor. And his
reply was, no, you
cannot do that, because the experiment has already been done and you would be
wasting time. This
was in about 1947 or so, and it seems to have been the general policy then to
not try to repeat
psychological experiments, but only to change the conditions and see what
happened.

Nowadays, there's a certain danger of the same thing happening, even in the
famous field of physics.
I was shocked to hear of an experiment being done at the big accelerator at
the National
Accelerator Laboratory, where a person used deuterium. In order to compare
his heavy hydrogen
results to what might happen with light hydrogen, he had to use data from
someone else's experiment
on light hydrogen, which was done on a different apparatus. When asked why,
he said it was
because he couldn't get time on the program (because there's so little time
and it's such expensive
apparatus) to do the experiment with light hydrogen on this apparatus because
there wouldn't be any
new result. And so the men in charge of programs at NAL are so anxious for
new results, in order to
get more money to keep the thing going for public relations purposes, they
are destroying -- possibly
-- the value of the experiments themselves, which is the whole purpose of the
thing. It is often hard
for the experimenters there to complete their work as their scientific
integrity demands.

All experiments in psychology are not of this type, however. For example,
there have been many
experiments running rats through all kinds of mazes, and so on -- with little
clear result. But in 1937 a
man named Young did a very interesting one. He had a long corridor with doors
all along one side
where the rats came in, and doors along the other side where the food was. He
wanted to see if he
could train the rats to go in at the third door down from wherever he started
them off. No. The rats
went immediately to the door where the food had been the time before.

The question was, how did the rats know, because the corridor was so
beautifully built and so
uniform, that this was the same door as before? Obviously there was something
about the door that
was different from the other doors. So he painted the doors very carefully,
arranging the textures on
the faces of the doors exactly the same. Still the rats could tell. Then he
thought maybe the rats were
smelling the food, so he used chemicals to change the smell after each run.
Still the rats could tell.
Then he realized the rats might be able to tell by seeing the lights and the
arrangement in the
laboratory like any commonsense person. So he covered the corridor, and still
the rats could tell.

He finally found that they could tell by the way the floor sounded when they
ran over it. And he
could only fix that by putting his corridor in sand. So he covered one after
another of all possible
clues and finally was able to fool the rats so that they had to learn to go
in the third door. If he
relaxed any of his conditions, the rats could tell.

Now, from a scientific standpoint, that is an A-number-one experiment. That
is the experiment that
makes rat-running experiments sensible, because it uncovers that clues that
the rat is really using --
not what you think it's using. And that is the experiment that tells exactly
what conditions you have to
use in order to be careful and control everything in an experiment with
rat-running.

I looked up the subsequent history of this research. The next experiment, and
the one after that,
never referred to Mr. Young. They never used any of his criteria of putting
the corridor on sand, or
being very careful. They just went right on running the rats in the same old
way, and paid no attention
to the great discoveries of Mr. Young, and his papers are not referred to,
because he didn't discover
anything about the rats. In fact, he discovered all the things you have to do
to discover something
about rats. But not paying attention to experiments like that is a
characteristic example of cargo cult
science.

Another example is the ESP experiments of Mr. Rhine, and other people. As
various people have
made criticisms -- and they themselves have made criticisms of their own
experiments -- they
improve the techniques so that the effects are smaller, and smaller, and
smaller until they gradually
disappear. All the para-psychologists are looking for some experiment that
can be repeated -- that
you can do again and get the same effect -- statistically, even. They run a
million rats -- no, it's
people this time -- they do a lot of things are get a certain statistical
effect. Next time they try it they
don't get it any more. And now you find a man saying that is is an irrelevant
demand to expect a
repeatable experiment. This is science?

This man also speaks about a new institution, in a talk in which he was
resigning as Director of the
Institute of Parapsychology. And, in telling people what to do next, he says
that one of things they
have to do is be sure to only train students who have shown their ability to
get PSI results to an
acceptable extent -- not to waste their time on those ambitious and
interested students who get only
chance results. It is very dangerous to have such a policy in teaching -- to
teach students only how to
get certain results, rather than how to do an experiment with scientific
integrity.

So I have just one wish for you -- the good luck to be somewhere where you
are free to maintain
the kind of integrity I have described, and where you do not feel forced by a
need to maintain your
position in the organization, or financial support, or so on, to lose your
integrity. May you have that
freedom.

Last mod.: January 26, 1997 - MLO (mailto:loreti@padova.infn.it)

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