Popperian falsifiability – Falsifiabilism and critical rationalism

Popperian falsifiability

Karl Popper remarked that general relativity made it possible to make predictions which very well might not have been verified, whereas other theories found confirmation in everything. Moreover, Einstein himself said that there is no logical method to construct a theory. Popper concluded that the scientific method consists of making guesses that can be tested against experience. Popper’s purpose in defining falsifiability was not to change the proven scientific method. In his own words, he “tends to think that we should try to find out what scientists ‘must’ do”, but he finds this method in Einstein.

To this end, Karl Popper invites us to distinguish falsifiability in the technical sense from a more common falsifiability used in everyday life outside of any scientific framework. Indeed, for Popper, falsifiability only concerns the need for a theory, if it wants to be empirical, to be logically contradicted by basic statements.

The latter must respect a material requirement: the basic statements must have an interpretation in terms of intersubjective observations. The material requirement does not mean that the basic statements must be possible in fact. Chalmers mentions “the brick fell in the air when it was dropped” as an example of a basic statement which is a potential contradiction of Newton’s law of gravitation. This is an impossible statement in fact, but it nevertheless meets the material requirement, because it could be observed with current technology, for example, if a law other than gravity were to come into play. Formally, there is only a question of statements and their logical relations, but the statements must have an empirical interpretation. Alain Boyer explains that the empirical character of basic statements can only be included in falsifiability from an informal angle. Despite its inevitable informal aspect, Popper is aware that this empirical character is important and is a necessary condition for the scientific process. Material requirement is an integral part of falsifiability: Zahar says that a physical law, as Duhem well remarked, is not just a sequence of symbols, but a formula with an interpretation.  He explains that otherwise one could evade a rebuttal by changing the meaning of the terms that go into the formulation of a scientific hypothesis. This is echoed by Boyer: “These kinds of ‘immunizing strategies’ amount to surreptitiously changing theory”.

There is no problem specific to a particular refutation in the requirements of falsifiability which are described above. All this is done naturally within a theoretical framework without having to perform any specific observation. Even empiricalness can be stated naturally using background knowledge (about observation), without having to make any observation. This material requirement which is necessarily informal is part of the empirical meaning of the theory which must be fixed in advance. However, Popper explains and this is echoed by Lakatos that methodological decisions must be made to accept or reject a potential contradiction and thus reject or corroborate the theory through observations. As Thornton mentions, Popper placed great emphasis on distinguishing between this methodological aspect of science and the logical aspect of falsifiability.

In the scientific method as understood by Popper, the methodological decisions that serve to disprove a theory are not made through a strict and systematic procedure and they do not have the force of law in the rejection of the theory and replacing it with another. Popper is aware of the problem of indeterminacy: the refutation of a theory is at most the corroboration of another theory among several other possible ones—it does not make it possible to rigorously choose among the set of possible scientific theories. It is therefore necessary to make conjectures. Finding the right conjecture and testing it so that it can succeed the disproved theory can take time. In this context, Popper recognizes that non-refutable statements or theories can play an important role in the scientific method by imposing constraints on the theories to be considered in making those conjectures. He proposes the name “metaphysical research program” for these unscientific theories.

According to Popper, the testing of a theory by the scientific method can never be used to justify or even logically reject the theory as Duhem’s thesis says, unless one accepts auxiliary hypotheses as unproblematic and contextual or background knowledge, a refutation or corroboration is never rigorously justified by logic, but, still according to Popper, “it does not justify skepticism or relativism”.

Imprecision relating to tests and consecutive scientific results, and heuristics

The inevitable imprecision of test results, and therefore their correlative falsifiability, together with the fact that it is equally impossible to completely avoid the introduction of elements of subjectivity, makes scientific work (and the results it produces) always open to criticism, therefore always potentially renewable or heuristic: since any scientific test is imperfect or (relatively) imprecise, it is always possible to assume the existence of errors whose resolution would be a source of discovery of an increase in knowledge. Moreover, this imperfection inherent in any scientific test can constitute this part of the unknown which is possibly knowable by the testing of new initial conditions.

The universe of true science cannot therefore be a closed universe, but is necessarily an open universe. It cannot rest on solid foundations (or “ultimate” as Karl Popper puts it), but on pilings ever deeper into the mud. And a science understood in the sense of Karl Popper can never be true (in the sense of certain truth), but always incomplete, imprecise, not sufficient, therefore “false” in relation to a hypothetical certain truth, which remains for Karl Popper a “guiding idea” and metaphysical, but also necessary for progress of scientific research.

This is the essential reason why, the “game of science” is logically endless.

Falsifiabilism and critical rationalism

The school of thought which uses refutability as a philosophical principle is known as critical rationalism or falsifiabilism, but the latter term also refers to the dogmatic, naive and sophisticated refutationisms of Lakatos which are a reconstruction of the history of the Popper’s philosophy which was proposed by Lakatos with the aim of criticizing and possibly improving it, claiming that it did not take account of Duhem’s thesis — criticisms and proposals for improvement which led, according to Harman, to a break between the two. In 1974, Lakatos asked if Popper’s refutationism was naïve or sophisticated. Popper replied that Lakatos distorted his intellectual history with these terminological distinctions.

Terminology

Already in 1962, Popper had proposed the expression critical rationalism to identify his philosophy. In 1978, he mentioned that he preferred to avoid the term falsifiabilism. More recently, the term falsifiabilism has been used positively, for example by David Miller, as a synonym for critical rationalism.

Critical rationalism and Duhem’s thesis

It is recognized that Popper was well aware of Duhem’s thesis and that at the level of the logic of refutability this thesis does not cause any difficulty. On this subject, Thornton explains that Popper’s logic of falsifiability is very simple, but that at the methodological level the situation is more complex. He mentions that Popper has repeatedly explained that even if a theory is refutable, it is impossible, in accordance with Duhem’s thesis, to refute it rigorously. Nevertheless, Popper mentioned in Conjectures and Refutations and elsewhere, as explained by Thornton, that despite Duhem’s thesis, it is possible to refute a theory with the help of contextual knowledge that one does not question. Zahar describes a solution to Duhem’s problem which he attributes to Popper and to Duhem himself. Popper adds that in any case, the fact remains that one can refute the system as a whole, the theory with the contextual knowledge, and hope that one will find with the help of other tests the part that is at fault. So, on a methodological level, Popper accepted Duhem’s thesis, but continued to talk about refutations. Because of this, Popper is criticized for not having taken seriously the practical aspect of Duhem’s thesis. For Lakatos, there is no refutation of a theory because of observations that contradict it. For example, it was not the contradictory observations, but the superiority of Einstein’s theory, which made it possible to reject Newton’s theory. Without the latter, even taking into account contextual knowledge, there would have been no rejection. Popper replied that he does not confuse the refutation of a theory with its rejection and that the choice to accept or reject a theory depends on several factors such as the other theories available. Mark Blaug confirms that Popper was always acutely aware of this “tenacity principle”. For this reason, he asserts that Popper’s refutationism is sophisticated and not naïve. However, the literature remains ambiguous on this subject. For example, in his recent article on Popper in the Stanford Encyclopedia of Philosophy, Thornton mentions that Popper’s distinction between logical rebuttal and methodological rejection does “not do justice” to the tenacity principle.

Sophisticated refutationism

Imre Lakatos, a disciple of Popper, in his book Proofs and Refutations, proposed “sophisticated refutationism” according to which a theory can only be refuted by another theory. Zahar has mentioned that this sophisticated refutationism of Lakatos, as much as one might attribute to Popper, requires Popperian refutation.

(Includes texts from Wikipedia translated and adapted by Nicolae Sfetcu)