This is a small fragment of my research project, developed during my research internship at the Institute of Economic Affairs in London.

The Positivist Model and Popper´s contribution:

 We can define “positivism” in a broad sense like the school of thought which establishes that only the scientific knowledge is that one true knowledge. According to this assertion, every knowledge must be analyzed and proved against experience, so as to consider its quality of “scientific” or not.

In this way, several methodological propositions arose during the nineteenth century, highlighting authors like Auguste Comte and John Stuart Mill, maximum exponents of empiricism. In addition, in the twentieth century we can point out other important authors like Bertrand Russell or Ludwig Wittgenstein, whose works inspired the constitution of “The Vienna Circle”. This group of intellectuals developed a great influence over the positivist logic, with the goal of establishing one single and true method for all sciences, which is no other but the experimental method own of the natural sciences. The rest, they say, is pure metaphysic. This is the origin of the called “methodological monism”.

However, this initial positivism was essentially influenced by the inductivism. It will be in 1.934 when a young Karl Popper publishes his “Logic of Scientific Knowledge”. In this work, Popper focus on a key question: how does scientific knowledge grows? The main task of the logic of scientific knowledge is to study the process (method) whereby the researcher lays down a set of hypothesis and after that, he proves them against the experience through the observation and experiment. Said this, Popper asserts that some people think the empiric sciences can only be those characterized by the inductivist method. The logic of all scientific knowledge is equal to inductivism:

“It is usual to call an inference inductive if it passes from singular statements (sometimes also called particular statements), such as accounts of the result of observations or experiments, to universal statements, such as hypothesis or theories.”  

 Despite the weight of inductivism in the positivist logic, Popper refuses it. As he follows:

“Now it is far from obvious, from a logical point of view, that we are justified in inferring universal statements from singular ones, no matter how numerous; for any conclusion drawn in this way may always turn out to be false: no matter how many instances of white swans we may have observed, this does not justify the conclusion that all swans are white.”

 Then, refused the inductivism, Popper proceeds to explain his “deductive method of testing”. According to this philosopher, for each new theory advanced by the researcher, its conclusions are obtained by deductive logical means. Then, these conclusions might be compared with other relevant (scientific) statements in order to get rational relations between them (such as equivalence relations, compatibility or incompatibility, etc). Therefore, Popper establishes four main test lines in the course of analyzing a new theory:

1. Logical comparison of conclusions among them so as to guarantee its consistency.

2. Inquiry of the logical form of the theory, in order to determine whether it is empiric (scientific) or tautological.

3. Comparison with other theories and acknowledge whether or not the new theory supposes a scientific advance.

4. Finally, contrasting the theory with the results offered by empirical evidence.

Conclusions which are supported by theories that have already been accepted do not admit difficulties. Statements which are not derived from current theory, and more specially those that contradict it, are the statements that concern to the method of testing.

Accordingly, Popper defines two important types of decisions:

“If this decision is positive, that is, if the singular conclusions turn out to be acceptable, or verified, then the theory has, for the time being, passed its test: we have found no reason to discard it. But if the decision is negative, or in other words, if the conclusions have been falsified, then their falsification also falsifies the theory from which they were logically deduced.”

 Popper´s “deductive method of testing” leads to his famous demarcation criterion. This criterion attempts to distinguish sharply on one hand between empiric sciences, and on the other hand, between logic, mathematics and metaphysics.

Nevertheless, there are two crucial considerations to point out when Popper asserts that the base of his criterion is falsifiability. First of all, we must recall that under this system a positive decision may support a theory just temporarily (i.e. while the empirical evidence does not prove it contrary) and instead, a negative decision can overthrow it forever. And secondly, positivism denies that knowledge which can not be verified by experience. On the contrary, Popper indicates that a theory can never be verified. Thus, because of this impossibility, Popper gets away far from inductivism and lays down a demarcation based in falsifiability, which admits scientific knowledge not in a positive sense but in a negative sense:

“My proposal is based upon an asymmetry between verifiability and falsifiability; an asimmetry which results from the logical form of universal statements. For these are never derivable from singular statements, but can be contradicted by singular statements.” 

 In fact, we can conclude that Popper has made a huge contribution redefining a more “sober” positivism within the called “critic rationalism”.