Karl Popper on the Line Between Science & Pseudoscience
It’s not immediately clear, to the layman, what the essential difference is between science and something masquerading as science: pseudoscience. The distinction gets at the core of what comprises human knowledge: How do we actually know something to be true? Is it simply because our powers of observation tell us so? Or is there more to it?
Sir Karl Popper (1902-1994), the scientific philosopher, was interested in the same problem. How do we actually define the scientific process? How do we know which theories can be said to be truly explanatory?
He began addressing it in a lecture, which is printed in the book Conjectures and Refutations: The Growth of Scientific Knowledge (also available online):
When I received the list of participants in this course and realized that I had been asked to speak to philosophical colleagues I thought, after some hesitation and consultation, that you would probably prefer me to speak about those problems which interest me most, and about those developments with which I am most intimately acquainted. I therefore decided to do what I have never done before: to give you a report on my own work in the philosophy of science, since the autumn of 1919 when I first began to grapple with the problem, ‘When should a theory be ranked as scientific?’ or ‘Is there a criterion for the scientific character or status of a theory?’
Popper saw a problem with the number of theories he considered non-scientific that, on their surface, seemed to have a lot in common with good, hard, rigorous science. But the question of how we decide which theories are compatible with the scientific method, and those which are not, was harder than it seemed.
It is most common to say that science is done by collecting observations and grinding out theories from them. Charles Darwin once said, after working long and hard on the problem of the Origin of Species,
My mind seems to have become a kind of machine for grinding general laws out of large collections of facts.
This is a popularly accepted notion. We observe, observe, and observe, and we look for theories to best explain the mass of facts. (Although even this is not really true: Popper points out that we must start with some a priori knowledge to be able to generate new knowledge. Observation is always done with some hypotheses in mind–we can’t understand the world from a totally blank slate. More on that another time.)
The problem, as Popper saw it, is that some bodies of knowledge more properly named pseudosciences would be considered scientific if the “Observe & Deduce” operating definition were left alone. For example, a believing astrologist can ably provide you with “evidence” that their theories are sound. The biographical information of a great many people can be explained this way, they’d say.
The astrologist would tell you, for example, about how “Leos” seek to be the centre of attention; ambitious, strong, seeking the limelight. As proof, they might follow up with a host of real-life Leos: World-leaders, celebrities, politicians, and so on. In some sense, the theory would hold up. The observations could be explained by the theory, which is how science works, right?
Sir Karl ran into this problem in a concrete way because he lived during a time when psychoanalytic theories were all the rage at just the same time Einstein was laying out a new foundation for the physical sciences with the concept of relativity. What made Popper uncomfortable were comparisons between the two. Why did he feel so uneasy putting Marxist theories and Freudian psychology in the same category of knowledge as Einstein’s Relativity? Did all three not have vast explanatory power in the world? Each theory’s proponents certainly believed so, but Popper was not satisfied.
It was during the summer of 1919 that I began to feel more and more dissatisfied with these three theories–the Marxist theory of history, psychoanalysis, and individual psychology; and I began to feel dubious about their claims to scientific status. My problem perhaps first took the simple form, ‘What is wrong with Marxism, psycho-analysis, and individual psychology? Why are they so different from physical theories, from Newton’s theory, and especially from the theory of relativity?’
I found that those of my friends who were admirers of Marx, Freud, and Adler, were impressed by a number of points common to these theories, and especially by their apparent explanatory power. These theories appeared to be able to explain practically everything that happened within the fields to which they referred. The study of any of them seemed to have the effect of an intellectual conversion or revelation, opening your eyes to a new truth hidden from those not yet initiated. Once your eyes were thus opened you saw confirming instances everywhere: the world was full of verifications of the theory.
Whatever happened always confirmed it. Thus its truth appeared manifest; and unbelievers were clearly people who did not want to see the manifest truth; who refused to see it, either because it was against their class interest, or because of their repressions which were still ‘un-analysed’ and crying aloud for treatment.
Here was the salient problem: The proponents of these new sciences saw validations and verifications of their theories everywhere. If you were having trouble as an adult, it could always be explained by something your mother or father had done to you when you were young, some repressed something-or-other that hadn’t been analysed and solved. They were confirmation biasmachines.
What was the missing element? Popper had figured it out before long: The non-scientific theories could not be falsified. They were not testable in a legitimate way. There was no possible objection that could be raised which would show the theory to be wrong.
In a true science, the following statement can be easily made: “If x happens, it would show demonstrably that theory y is not true.” We can then design an experiment, a physical one or sometimes a simple thought experiment, to figure out if x actually does happen. It’s the opposite of looking for verification; you must try to show the theory is incorrect, and if you fail to do so, thereby strengthen it.
Pseudosciences cannot and do not do this–they are not strong enough to hold up. As an example, Popper discussed Freud’s theories of the mind in relation to Alfred Adler’s so-called “individual psychology,” which was popular at the time:
I may illustrate this by two very different examples of human behaviour: that of a man who pushes a child into the water with the intention of drowning it; and that of a man who sacrifices his life in an attempt to save the child. Each of these two cases can be explained with equal ease in Freudian and in Adlerian terms. According to Freud the first man suffered from repression (say, of some component of his Oedipus complex), while the second man had achieved sublimation. According to Adler the first man suffered from feelings of inferiority (producing perhaps the need to prove to himself that he dared to commit some crime), and so did the second man (whose need was to prove to himself that he dared to rescue the child). I could not think of any human behaviour which could not be interpreted in terms of either theory. It was precisely this fact–that they always fitted, that they were always confirmed–which in the eyes of their admirers constituted the strongest argument in favour of these theories. It began to dawn on me that this apparent strength was in fact their weakness.
Popper contrasted these theories against Relativity, which made specific, verifiable predictions, giving the conditions under which the predictions could be shown false. It turned out that Einstein’s predictions came to be true when tested, thus verifying the theory through attempts to falsify it. But the essential nature of the theory gave grounds under which it could have been wrong. To this day, physicists seek to figure out where Relativity breaks down in order to come to a more fundamental understanding of physical reality. And while the theory may eventually be proven incomplete or a special case of a more general phenomenon, it has still made accurate, testable predictions that have led to practical breakthroughs.
Thus, in Popper’s words, science requires testability: “If observation shows that the predicted effect is definitely absent, then the theory is simply refuted.” This means a good theory must have an element of risk to it. It must be able to be proven wrong under stated conditions.
From there, Popper laid out his essential conclusions, which are useful to any thinker trying to figure out if a theory they hold dear is something that can be put in the scientific realm:
1. It is easy to obtain confirmations, or verifications, for nearly every theory–if we look for confirmations.
2. Confirmations should count only if they are the result of risky predictions; that is to say, if, unenlightened by the theory in question, we should have expected an event which was incompatible with the theory–an event which would have refuted the theory.
3. Every ‘good’ scientific theory is a prohibition: it forbids certain things to happen. The more a theory forbids, the better it is.
4. A theory which is not refutable by any conceivable event is nonscientific. Irrefutability is not a virtue of a theory (as people often think) but a vice.
5. Every genuine test of a theory is an attempt to falsify it, or to refute it. Testability is falsifiability; but there are degrees of testability: some theories are more testable, more exposed to refutation, than others; they take, as it were, greater risks.
6. Confirming evidence should not count except when it is the result of a genuine test of the theory; and this means that it can be presented as a serious but unsuccessful attempt to falsify the theory. (I now speak in such cases of ‘corroborating evidence’.)
7. Some genuinely testable theories, when found to be false, are still upheld by their admirers–for example by introducing ad hoc some auxiliary assumption, or by re-interpreting the theory ad hoc in such a way that it escapes refutation. Such a procedure is always possible, but it rescues the theory from refutation only at the price of destroying, or at least lowering, its scientific status. (I later described such a rescuing operation as a ‘conventionalist twist’ or a ‘conventionalist stratagem’.)
One can sum up all this by saying that the criterion of the scientific status of a theory is its falsifiability, or refutability, or testability.
Finally, Popper was careful to say that it is not possible to prove that Freudianism was not true, at least in part. But we can say that we simply don’t know whether it’s true because it does not make specific testable predictions. It may have many kernels of truth in it, but we can’t tell. The theory would have to be restated.
This is the essential “line of demarcation,“ as Popper called it, between science and pseudoscience.
Read more at fs.blog
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James McGinn
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fs.blog:
Some genuinely testable theories, when found to be false, are still upheld by their admirers–for example by introducing ad hoc some auxiliary assumption, or by re-interpreting the theory ad hoc in such a way that it escapes refutation.
JMcG:
So true!
Did you hear the one about the guy that goes to buy a suit?
http://www.thunderbolts.info/forum/phpBB3/viewtopic.php?f=8&t=16319
James McGinn / Solving Tornadoes
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jerry krause
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Hi fs.blog,
You (whomever you are) quoted Popper: “I therefore decided to do what I have never done before: to give you a report on my own work in the philosophy of science, since the autumn of 1919 when I first began to grapple with the problem, ‘When should a theory be ranked as scientific?’ or ‘Is there a criterion for the scientific character or status of a theory?’´ Then you wrote: We observe, observe, and observe, and we look for theories to best explain the mass of facts. (Although even this is not really true: Popper points out that we must start with some a priori knowledge to be able to generate new knowledge. Observation is always done with some hypotheses in mind–we can’t understand the world from a totally blank slate.”
Both Popper and you clearly believe science is about explanation. I doubt, but clearly do not know, if he, or you, have read what Newton wrote near the end of The Principia (as translated by Motte): “But hitherto I have not been able to discover the cause of those properties of gravity from phenomena and I frame no hypotheses; for whatever is not deduced from the phenomena is to be called an hypothesis; and hypotheses, whether metaphysical or physical, whether of occult qualities or mechanical, have no place in experimental philosophy. In this philosophy particular propositions are inferred from the phenomena and afterwards rendered general by induction. Thus it was that the impenetrability, the mobility, and the impulsive force of bodies, and the laws of motion and of gravitation, were discovered. And to us it is enough that gravity does really exist, and act according to the laws which we have explained, and abundantly serves to account for all the motions of celestial bodies, and of our sea.”
What I understand from Newton words is that it not important what gravity is, but what is important is what gravity does.
What seems critically important, to me, is Newton’s reference to having explained the motions of the seas. Here I understand that Newton is referring to his explanation of semidiurnal tides and the greater importance of the moon relative to the much more massive sun according to the laws of gravitation. For not all oceans and seas have the same motions.
I repeat that you wrote: “Observation is always done with some hypotheses in mind–we can’t understand the world from a totally blank slate.”
Absolutely false. I imagine that I have ‘sailed’ my boat of the Mediterranean Sea, which doesn’t have a discernible tide all my life and then one day I sail my boat though the Strait of Gibraltar and I am not, in a day or two, going to notice the very observable tides of the Atlantic Ocean unless I have some hypotheses in mind?
It does not matter how many hypotheses you have in mind, if you have no observations you are trying to understand the world from a totally blank slate.
Have good day, Jerry
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Ken Hughes
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Agree that what gravity does is important. Disagree with you on what gravity is. It is even more important what gravity is, if we are to fully understand the workings of the cosmos.
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HEITOR DE PAOLA
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As a Freudian psycho-analyst I read Professor Popper early in my professional life. I can state that his insightful ideas were very helpful to my clinical approach to patients. Knowing that my assessment of a patient is not the ultimate truth but only a hypotheses that had to be tested was a remarkable help to gauge my omniscient temptations. This article besides being helpful is akin to my own conclusions about Professor Popper remarkable contributions to scientific philosophy.
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Rosie Langridge
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I found the historical explanation given by fs. very helpful, and also your comment, Heitor which illuminates it.
I do wonder if “hypothesis” , however useful as a term in Popper’s work, has become formulaic and unhelpful. Perhaps what Popper was calling a hypothesis we might now term a belief system or world view? The problem described in fs.’s piece is the “heads I win, tails you lose” phenomenon and I’m not sure it really has a lot to tell us about the science today – though plenty about people with an agenda.
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Herb Rose
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Einstein’s physics is based on the photon (particle nature of light) a result of the photoelectric effect. The reasoning being that a wave would take time to transfer enough energy to dislodge an electron. The error in this reasoning is that a wave doesn’t need to transfer all the energy to an atom in a crystal, just enough to change the balance between the repelling and attractive forces in the crystal. The next jump of faith, for which there is no supporting evidence, is that the speed of light is constant. From this came E=mc^2. When this prediction was tested by the energy given off from radioactive decay it failed and the neutrino was created to preserve the theory. Since then a myriad of invisible and untestable entities have been created to perpetuate modern physics which is pseudoscience.
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Ken Hughes
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Good luck with your theory then Herb.
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Deivis
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Speed of light is a constant i.e. ratio of length of meter and duration of second or space and time is a constant. That is why we see objects. Our senses make light into an object which is touchable and we can label it. Initially length of meter was based on dimensions of our planet i.e. the distance from equator to the pole divided into 10 000 000 meters. Then 1 cubic meter of water was assigned mass of 1 000 kg. One rotation of our planet around it’s axis was divided into 360*240 seconds. This number is based on our bone structure. We divide one circle into 360 degrees. This number is the basis of geometry. With these numbers and measurements the whole science of physics has emerged. So we see objects and distances between instead of pure light. As rotation of planets is not constant but our bone structure remains the same duration of second is not constant. So to make atom into an object scientists connected duration of second with cesium atom. So we created more and more words unrelated with our senses to describe that which is beyond senses i.e. chemistry and beyond.
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jerry krause
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Hi Deivis,
You concluded: “So we created more and more words unrelated with our senses to describe that which is beyond senses i.e. chemistry and beyond.”
You began: “Speed of light is a constant.” How did we determine this by our unaided senses? And you wrote: “Initially length of meter was based on dimensions of our planet” Who has measured the dimensions of our planet to the nearest meter?
You write about history at the same time you seem to ignore what prehistoric people had done. Like Stonehenge which those, who have studied it, conclude did not first begin with them placing stones in circles but by digging a circular trench and piling the dirt in a circular bank and digging 56 regularly spaced holes which also defined a reasonably precise circle. And these circular earthworks were quite large and the spacing between the 56 holes was within a few inches of 5 meters. Which maybe could be make more precisely 5 meters by choosing the right circumference defined by the holes which had an very approximate (not all the same) diameter of a meter.
And we absolutely know today that the units of length known as the English rod (16.5ft) and 5 meters only differ by a few inches. And we know (historically) that the lengths of the foot and the meter were defined well after the prehistoric time when it seems Stonehenge was begun by human activities (and knowledge).
Have a good day, Jerry
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Deivis
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How did we determine that speed of light is a constant by our unaided senses? This comes as experience in meditation. When you feel your ever changing body, passing thoughts, air moving in and out of your body you notice that view in your eyes is constantly changing. So something non-changing is holding this. And it is constant. So ancient people felt this. Einstein used this knowledge in his theory of relativity.
Length of meter was determined after French revolution. I read this in Wikipedia.
Prehistoric people used other words than today. So we can not put ancient technology in today’s concepts. We do reverse engineering but past will remain a secret to us.
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jerry krause
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Hi Deivis,
Thank you for your response, It is good to be clear about your methods.
Have a good day, Jerry
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jerry krause
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Hi Fellows,
I have a hypothesis that you who have commented are men because of your first names, but I could be wrong. And then I realized I had no clue who fsblog was.
Until I discovered PSI I, with years (decades) of experience as a chemist, I had never heard of Karl Popper. I challenge anybody to inform me about an introductory, but college level, science (any commonly accepted science) textbook) in which one can find the name Karl Popper.
I have read that Lewis Agassiz forbid his beginning students to read or talk with anyone about his assignments until he gave them permission to do so. I have read that Richard Feynman discouraged, if not forbid, his students from doing literature searches. The reason? I have read both of these professors told their students that if they did they were likely to never study anything new. For if they read about the hypotheses of others their minds would not be a blank slate and knowing about these hypotheses of others would likely hinder them from seeing everything that could be seen.
Two days earlier, one of my essays (https://principia-scientific.com/diffuse-solar-radiation-a-history/) was posted by John O’. In it I questioned if the NOAA designers of the instrumentation of the SURFRAD project had included an instrument to measure what is termed Diffuse Solar. And based on a figure of data measured at the Fort Peck site on June 1, 1996, which did not include any Diffuse Solar, I questioned: what in this figure could have prompted the NOAA scientists to include the Diffuse Data at a new site by December 1, 1996?
To date, even though there have been a few comments, no one has directly tried to present their hypothesis about what these NOAA scientist might have seen once they possibly saw the first data that was being measured by their possibly first design.
In my mind (which is maybe a blank), this article and my essay are very closely related. Which is why I draw your attention to it.
Have a good day, Jerry
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