New Logics for the Verificationistic Enterprise

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The project aims to take a fresh look at the verificationistic theory of meaning, which holds that the meaning of a proposition is given by the method of its verification, and the consequences on logical principles such a theory will imply.. That adopting such a verificationistic theory should lead to logical revision has been extensively argued by Michael Dummett. He claimed that a serious endoresement of verificationism had to result in the endorsement of a constructive logic. Usually it is assumed that this constructive logic has to be intuitionistic logic. However, the main thesis of the project is the following: If unrealistic assumptions are given up, the verificationistic account of meaning does not, as Dummett held, unequivocally point towards intuitionistic logic. Instead, it gives support to certain non-classical logics that are either not yet in clear view, or even haven't been discovered yet. It is my goal to spell out the requirements on such logics and to test different systems for their suitability. The unreasonable assumptions I mentioned are these: (A) That a verificationistic theory of meaning of empirical discourse can employ the characterization of negation found in intuitionistic mathematics; and (B) that verifications (outside of mathematics) are certain and definite affairs, such that no mechanism of revision needs to be supplied. In terms of logical systems, giving up (A) points to a constructive logic with a so-called strong negation operator, while giving up (B) calls for some kind of non-monotonicity. The most promising route seems to lead in the direction of a non-monotonic version of Nelson's logic N3, but I want to explore a wider range of other possibilities as well. I am confident that this research will bring insights in a variety of fields, such as the philosophy of language, philosophical logic and the philosophy of science. I hope to describe and motivate a number of logical systems and to contribute to more general philosophical discussions, for example to the question whether a quantitative or qualitative conception of confirmation (or possibly both) should be adopted.