Avoiding mistakes is a narrow-minded ideal. If we don’t dare face those challenges that are so difficult as to make the error almost inevitable, knowledge will not be developed. It is from our more daring theories, including those that are wrong, that we learn the most from. No one can avoid making mistakes: but the important thing is to learn from them”.

The scientific philosophy of Karl Popper starts with a criticism of the idea that a scientific theory can be built using a process that goes from facts to generalizations. Theories are always the result of “conjectures” that also contain intuitive and imaginary elements that cannot be analyzed rationally.

For Popper human knowledge arises from the human attitude towards solving the problems they encounter, in particular when there is a contradiction between the expected outcome of a theory and the actual facts observed.

However, in science it is not enough to “observe”: it is also necessary to know what to observe. Observation is never neutral, but is always ingrained with theory, to the point that it is impossible to distinguish the “facts” from the “opinions”, because the human mind subconsciously tends to superimpose its own thinking patterns, with its own categorizations, on top of the observed reality. Since we never possess facts, but only ever opinions, the result is the hypothetical and therefore fallible character of science:

 “The empirical (experimental) basis of objective science has nothing ‘absolute’ about it. […] Science does not rest on solid bedrock. It is like a building built on pillars”.

This leads to Popper’s well-known concept of falsifiability. Falsifiability is the criterion that distinguishes science from pseudo-science: a theory is scientific if, and only if, it can be falsified. To express it in the words of the philosopher himself: “It must be possible for a scientific system to be refuted by experience”.

The typical process of scientific knowledge is the hypothetico-deductive method, in which a hypothesis is taken and then serious attempts are made to try and falsify (disprove) it. The fact that a theory can be falsified means that it must be expressed in a logical and deductive form: one starts with a universal assertion with the aim of achieving a particular result in a closely concatenated manner that can be controlled experimentally.

However, as numerous as they may be, the experimental observations in favor of a theory can never definitively prove it: even one retraction is enough to refute it. The falsifiability criterion therefore emphasizes the ongoing temporary character of scientific theories.

On the other hand, Popper admits that often irrational ideas can pave the way to scientific ideas and therefore must not be considered “senseless and unintelligible”: metaphysics and the extra-rational can therefore play a positive role in scientific discovery.

The scientific model that emerges from Popper’s way of thinking is that of an ongoing revolution. It is therefore necessary to investigate how science reproduces and “grows”. Falsifiability must be pursued and theories must undergo strict controls that try to falsify them. Furthermore, the scientific community has established rules that make it possible to establish when a falsifying assertion is considered accepted and therefore efficient.

According to Popper, it is therefore necessary to establish a code of conduct (a “code of honor”) among scientists. Theories compete with one another: a neutral language that is common and intersubjective can be used each time to critically discuss the merits of the different theories without encountering difficulties in communication.

“Our choice is one of a series of theories that compete with one another, and far from being the application of an algorithm, it is an act of preference; and any preference of a theory over another is in its turn a conjecture of a higher order”. With the severity of controls, the pragmatic element of scientific work that cannot be easily framed within the rationality of a theoretical model re-emerges.

This does not mean that it is necessary to give up the search for objective truth, because it is thanks to errors that we have the possibility of drawing nearer to it, through a constantly evolving process of the elimination of what is fake. Truth becomes the regulatory ideal that makes the action of the scientist possible and that gives it a meaning.

Popper’s approach to science if therefore strongly anti-dogmatic, and is inspired by the criteria of what the philosopher himself defines as an “open society”: “The open society is open to several values, several visions of the philosophical world and several religious faiths, and a multitude of proposals for the solution of concrete problems and the greatest number of criticisms. The open society is open to the greatest number possible of different ideas and ideals that may even be in contrast to one another […]. The open society is closed only to those that are intolerant”.