RR0/rr0.org

<!--#include virtual="/header-start.html" -->
<title>Cargo Cult Science</title>
<meta content="https://www.lhup.edu/~DSIMANEK/cargocul.htm" name="url"/>
<meta content="Feynman, Richard P." name="author"/>
<meta content="Adapté d'un Caltech commencement address donné en 1974" name="copyright"/>
<!--#include virtual="/header-end.html" -->
<span class="source">Extrait de "Surely You're Joking, Mr. Feynman!"</span>
<p> 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.</p>
<p> 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.</p>
<p> 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.</p>
<p> A Esalen il y a des 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. </p>
<p> Une fois, je m'assis dans un bain où se trouvait une belle jeune fille assise avec un gars qui ne semblait pas la
  connaître. Tout de suite, je commençais à me dire, <q>Wow ! Comment vais-je entâmer la conversation avec cette belle
    femme nue ?</q></p>
<p> Je tente de réfléchir à quoi dire, lorsque le gars lui dit, <q>J'étudie, euh, les massages. Est-ce que je peux
  m'entraîner sur vous ?</q></p>
<p><q>Bien sûr</q>, dit-elle. They get out of the bath and she lies down on a massage table nearby. </p>
<p> I think to myself, <q>"What a nifty line! I can never think of anything like that!</q>" Il commence à frotter son
  gros orteil. <q>Je pense que je le sens</q>, dit-il. <q>Je sens une sorte de bosselure -- est-ce le pituitaire ? </q>
</p>
<p> I blurt out, <q>"You're a helluva long way from the pituitary, man!" </q></p>
<p> They looked at me, horrified — I had blown my cover — and said, "<q>It's reflexology!</q>" </p>
<p> I quickly closed my eyes and appeared to be meditating. </p>
<p> 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. </p>
<p> 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. </p>
<p> 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. </p>
<p> So we really ought to look into theories that don't work, and science that isn't science. </p>
<p> 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. </p>
<p> 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. </p>
<p> 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. </p>
<p> 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. </p>
<p> 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. </p>
<p> 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. </p>
<p> 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. </p>
<p> 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. </p>
<p> 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. </p>
<p> 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 </p>
<p> 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. </p>
<p> 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. </p>
<p> 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. </p>
<p> 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. </p>
<p> 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. </p>
<p> D'autres types d'erreurs sont plus caractéristiques d'une science médiocre. Lorsque j'étais à Cornell, j'ai souvent
  parlé aux gens du département de psychologie. Une des étudiantes me dit qu'elle voulait faire une expérience qui
  donnerait quelque chose comme ça -- il avait été trouvé par d'autres que dans certaines circonstances, X, les rats
  faisaient quelque chose, A. Elle était curieuse de savoir si, si elles changeait les circonstances en Y, ils feraient
  toujours A. Donc sa proposition était de faire l'expérience dans les circonstances Y et de voir s'ils faisaient
  toujours A. </p>
<p> Je lui ai expliqué qu'il était d'abord nécessaire de répeter dans son laboratoire l'expérience de l'autre personne —
  de la faire dans les conditions X pour voir si elle pouvait aussi avoir le résultat A, puis ensuite de les changer en
  Y et de voir si A changeait. Ensuite elle saurait si la véritable différence était la chose qu'elle pensait avoir sous
  contrôle.</p>
<p> Elle fut ravie de cette nouvelle idée, et alla voir son professeur. Et sa réponse fut, non, vous ne pouvez pas faire
  ça, parce que l'expérience a déjà été faite et que vous perdriez votre temps. C'était vers <a
      href="../../../4/7/index.html">1947</a> ou à peu près, et il semble avoir été la politique générale alors de ne
  pas tenter de reproduire les expériences psychologiques, mais seulement de changer les conditions et de voir ce qui se
  passait. </p>
<p> 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. </p>
<p> 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. </p>
<p> 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. </p>
<p> 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. </p>
<p> Maintenant, d'un point de vue scientifique, c'est une expérience A-numéro 1. C'est l'expérience qui 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. </p>
<p> 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. </p>
<p> Un autre exemple est les expériences ESP de M. Rhine, et d'autres gens. 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? </p>
<p> 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. </p>
<p> 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. </p>
<!--#include virtual="/footer.html" -->