# Abstract

In previous papers I have characterized four ways of reasoning in Peirce’s philosophy, and four ways of
reasoning in Computability Theory. I have established their correspondence on the basis of the four pairs
of choices regarding two dichotomies, respectively the dichotomy between two kinds of Mathematics and
the dichotomy between two kinds of Logic. In the present paper I introduce four principles of reasoning in
theoretical Physics and I interpret also them by means of the four pairs of choices regarding the above two
dichotomies. I show that there exists a meaningful correspondence among the previous three fourfold sets
of elements. This convergence of the characteristic ways of reasoning within three very different fields of
research - Peirce’s philosophy, Computability theory and physical theories - suggests that there exists a
general-purpose structure of four ways of reasoning. This structure is recognized as applied by Mendeleev
when he built his periodic table. Moreover, it is shown that a chemist-, applies all the above ways of
reasoning at the same time. Peirce’s professional practice as a chemist applying at the same time this
variety of reasoning explains his stubborn research into the variety of the possible inferences.