It’s not always clear in today’s world of fake news and demagoguery what the 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? Science has always been built upon our powers of observation, but all human observation is affected by bias.

Sir Karl Popper (1902-1994), known as the scientific philosopher, was interested in the same problem. In his era, science was tested through induction. Inductionionist science is not a posteriori, and, therefore, not empirical. An example of inductive reasoning is, “The coin I pulled from the bag is a penny. A second coin is also a penny. A third coin from the bag is a penny. Therefore, all the coins in the bag are pennies.” Inductive reasoning makes broad generalizations based on specific observations. Even if all of the premises are true in a hypothesis, inductive reasoning allows for the conclusion to be false.

Science, as we know it today, however, is empirical, thanks to Popper. Before Karl Popper, no one had attempted to create a philosophical understanding of what constitutes a scientific or a pseudoscientific claim.

Sir Karl ran into this problem in a concrete way, because he lived during a time when psychoanalytic theories were all the rage, meanwhile, Einstein was laying out a new foundation for the physical sciences with his famed Theory of Relativity. What made Popper particularly uncomfortable were popular 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?

Because they were confirmation bias machines. But what was the key to differentiating these biased theories from legitimate science? It didn’t take long for Popper to figure it out: The pseudoscientific theories could not be falsified, that is to say, they were not testable in a legitimate way. There was no possible objection that could be raised by a reasonable critique which would show the theory to be wrong.

“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.”

In the modern scientific community, 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 to determine conclusively if x actually does happen. It’s the exact opposite of looking for verification; the researcher must try to establish that the hypothesis is incorrect, and if they fail to do so, thereby strengthen it.

Pseudosciences cannot do this–they are not strong enough to hold up to this standard. As an example, Popper discussed Freud’s theories of the mind in relation to Alfred Adler’s so-called “individual psychology,” which was quite 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 noticed that whether the discussion was about Adler or Freud, no point of contention could be raised by an objective observer. If a man is honest, it is because of events that occurred in his early childhood. If a man is dishonest, it’s because of some trauma he underwent in his early childhood. The Adlerians and the Freudians were never wrong. And it was not clear how they could ever be wrong, as they could post-hoc tell a story about how any given phenomenon fit their theories perfectly. Everything in the world was to them further evidence for their respective theories.

Popper noted that Freud had exclusively related stories about how the past confirmed his theory, never claiming how a possible future state of events could disprove it. Between all of Freud’s extensive works on the different complexes and drives, every possible human action or mindset could be conveniently explained as originating from childhood experiences and conflicting unconscious mental agents. But Freud did not make any bold conjectures, and did not attempt to falsify his theory with truly scientific experiments. He had no predictions, and, thus, no falsifiability.

Popper contrasted the theories of Marx, Freud and Adler against Einstein’s Relativity, which made specific, independently-verifiable predictions, giving the specific conditions under which these predictions could be proven false. It turned out that Einstein’s predictions were proven true when tested, thus verifying the theory through attempts to refute it. However, the essential nature of the theory began to provide 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 succeeded in making accurate, testable predictions that have led to scientific breakthroughs.

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 clearly stated conditions. Popper laid out these conditions in his “Seven Essential Conclusions”:

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.’)

Popper’s Seven Essential Conclusions can be summed up by saying that the criterion of the scientific status of a theory lies in its falsifiability, or refutability, through hypothesis testing. 

Marxism certainly holds no weight on the scales of refutability, as the whole of Marx’ ideology is founded upon his bias. Whatever happens will always confirm its validity, regardless of relevance or reason. Thus its truth appears manifest to Marxists; and “unbelievers” are clearly people who did not want to see the manifest truth; who have willfully refused to accept it, either because it was against their class interest, or because they are blinded by the bourgeois brainwashing of their own repressions. Marxism isn’t a system of politics or economics so much as it is a religious cult, essentially the Scientology of economics. And religions, by virtue of their dependence on faith, cannot pass the falsifiability test. That is not to say that all religion is false, but faith is not a foundation for political science, much less economics. 

Astute readers will have noticed that Popper was very careful to say that it is not possible to prove that Freudianism was not true, at least in part. however, we can also say that it cannot be proven true, because it does not make specifically testable predictions. It may have many kernels of truth in it, but we can’t clearly separate these from the cleverly-masked assumptions and outright bias. The theory would have to be restated.

This is the essential “line of demarcation,“ as Popper called it, between science and pseudoscience.


  1. Brilliant article and I think it’s about time someone paid respects to the man who not only revolutionized science but influenced such great thinkers as Mises, Rothbard and Hoppe. Well done.


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