Logic: From Tolerance to Pluralism (2019 - 2023)
This project is funded by the DFG.
This project is funded by the DFG.
Alongside classical logic, there is a multitude of alternative logics these days. In contrast to logical monism, logical pluralism allows different logics to coexist as equals. The aim of this project is to develop a coherent and non-trivial form of logical pluralism. The thesis of logical pluralism is subject to several challenges. On the one hand, it has to be explained how it is possible that various argument forms can be correct. On the other hand, pluralism should not collapse into the trivial thesis that any logic goes. The form of logical pluralism envisaged in this project should therefore not only explain the plurality of diverse logics, but also enable a fruitful interaction between logics. The starting point for the formulation is Carnap's Principle of Tolerance. A historical analysis is the first step towards a modern version of logical pluralism. Carnap's Principle of Tolerance is based, on the one hand, on a meta-perspective on language, and, on the other hand, on a form of linguistic relativism. Both aspects need detailed investigation. The Principle of Tolerance is therefore the starting point for a systematic investigation of pluralism. In this systematic part of the project, methods from proof theory will be applied, and central questions, of a technical as well as a philosophical sort, such as the collapse argument, will be clarified. Furthermore, it serves as the basis for a fully worked-out formal theory, in which the central concept of logical deduction is explicated proof-theoretically by means of sequent calculi. These parts of the project will be brought together into a unified philosophical theory, with a corresponding epistemology and an inferentialist theory of meaning.