The criterion of falsifiability

In order to discern what a scientific theory is, first of all, it must be understood that science is an empirical method that is based on observation and inductive reasoning. This is to be contrasted to non-empirical methods, even those that are formulated by observation.  Not all observational experiments meet scientific standards (for example, pseudo-science or metaphysical methods such as astrology).

Einstein’s theory of gravitation was highly influential to Karl Popper’s intellectual pursuit in determining the scientific status of a theory.  Popper felt that the Marxist theory of history, Freud’s theory of psychoanalysis and Alfred Adler’s theory of individual psychology were dubious. He was not bothered by falsity, inexactness or immeasurability. Rather, he was disturbed by the fact that three theories replicated primitive myths instead of science. Popper opined that the theories of Marx, Adler and Freud were predominantly based on previous experience to constitute confirmation. However, it is questionable what exactly these theories confirmed.

There are many overlaps between each of the three theories as they can all describe and interpret any type of human behaviour. This fact, that they always worked to confirm something or give explanation for conduct, was why many thought the theories to be persuasive. Popper begged to differ. He argued that the apparently beneficial fact, that the theories always acted to confirm – explain and operate the same – was the major weakness of each.  Popper’s argument was formulated in the context of Einstein’s theory of gravitation.

In a nutshell, Einstein’s gravitational theory was developed by risk-taking prediction. According to the theory, heavy bodies (such as the moon or the sun) are the only bodies that can attract light. In effect, the light drawn from a star that is positioned close to the sun, would reach the earth in a way that looks as if the star has slightly moved away from the sun. This example can of course not be observed in reality because stars are not visible in the day; the beaming light of the sun blurs them (except for in the case of an eclipse). Accordingly, it is risk-taking to predict that the star would seem to be slightly shifted away from the sun. It can thus be contrasted to the three other theories of Marx, Freud and Adler.

The three theories of Marx, Freud and Adler can never be negated by prediction of human behaviour. They are compatible with the most abstract forms of human behaviour and will always operate to verify such behaviour. There is no risk involved in predicting the way humans will conduct themselves under each indifferent kind of theory. By contrast, much risk is found in the theory of gravitation enunciated by Einstein, as it can only be proven in the case of an eclipse.

In essence, Popper argued that confirmations should only be seriously considered as persuasive if they are the result of risky predictions. Further, that the more a scientific theory has the tendency to forbid particular things to happen, the better it is and that theories must be refutable by conceivable events in order to be scientific. Accordingly, theories should be testable. Once theories are subject to testability, they are refutable and they are more prone to greater risk. The influence that can be drawn from Einstein’s theory of gravitation is its satisfaction of the criterion of falsifiability. Marx, Freud and Adler got caught up in escaping falsification such that they destroyed the testable nature of their theories. The theories could neither be falsified nor tested, and thus they were not capable of attaining scientific status. This is mainly because the predictions drawn from the interpretations of the theories were too vague in order to constitute something that could be refuted. Vague predictions can hardly fail and are therefore irrefutable.

Non-scientific theories 

There are two types of non-scientific theories. First, a theory that is initially testable but proved to be false and re-interpreted to escape refutation.  Even if a theory is found to be false once tested, people may still believe in it – by re-interpreting it in a way that escapes its falsity. However, any false theory that is subject to a process designed to rescue it from refutation lowers its scientific status. For example, the Marxist theory of history and the coming social revolution involved testable predictions. Though, these predictions were falsified. Once proved to be false, followers of Marx did not accept the refutations. Rather, they re-interpreted the theories in order to make them agree – at the cost of adopting a vague approach that made the theories irrefutable. In so doing, the scientific statuses of the Marxist theories were forfeited to irrefutability and non-testability.

The second type of non-scientific theories are those that are non-testable and irrefutable from the start. That is, those theories according to which conceivable human behaviour is consistent and non-contradictory. Freud and Adler provided theories of such a type. This is not to say that the two theorists were in the wrong. However, no substantial claim to scientific status can be made of the theories because they cannot be tested by every day human conduct. Rather, everyday human conduct confirms the theories – but such daily confirmations are frivolous and overly vague in order to satisfy the criterion of falsification in science.  

Although some theories that cannot be refuted lack scientific significance – they do not lack importance.  Metaphysical (or non-scientific) theories are not meaningless, but they cannot be supported by meaningful empirical evidence. It must be remembered that Popper tried to propose a criterion of falsifiability with refutability and testability – but this was not due to any issue of meaningfulness or significance or truth or acceptability. His task was to solve the problem of distinguishing between statements of the empirical sciences and all other statements that are non-scientific. Popper called this problem the problem of demarcation. Accordingly, the criterion of falsifiability, which ranks statements as scientific if they are capable of conflicting with conceivable human behaviour, is aimed at solving this problem.