Aletheia, double negation and negation

Abstract: The definition of negation has to be referred to the totality of a theory and at last to what is defined as the organization of a scientific theory; in other words, the definition of negation is of a structural kind, rather than of an objective kind or a subjective kind. The paper starts by remarking that the ancient Greek word for truth was aletheia, which is a double negation, i.e. unveiling. Not before the 1968 the double negation law was re-evaluated, since it was recognized that its failure represents more appropriately than the failure of of excluded middle law the borderline between classical logic and almost all non-classical kinds of logic. Moreover, the failure of this law is easily recognized within a scientific text; this fact allows a new kind of logical analysis of a text. As an example, the analysis of Kolmogorov 1932 paper shows that he reasoned according to arguments of non-classical logic about the foundations of the intuitionist logic. The negation is defined as a unary operation which, under the problem of deciding whether a doubly negated proposition is equal to the corresponding affirmative proposition or not, leads to a subdivision into classical logic and intuitionist logic.