Feynman on Integrity

CARGO CULT SCIENCE by Richard Feynman

Adapted from the Caltech commencement address given in 1974.

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 UFOS, 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 shore 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 beautiful 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 babe?"

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 cheek 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 land with lots of good materials, and they want the same

thing to happen now. So they've arranged to imitate 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

like 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 explicitly say 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 try to give all of the information to

help others to judge the value of your contribution; not just the

information that leads to judgment 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 didn'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 the electron, after Millikan. If you

plot them as a function of time, you find that one is a little

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 that 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 closer 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 not to 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 are 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 this 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 want to 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

it 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 that 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 happens.

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 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 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 the 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 into 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 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 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 parapsychologists

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 and

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 it 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 the

things they have to do is be sure they 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.