Rational Agency from a Truth-Functional Perspective

Ekaterina Kubyshkina, Dmitry V. Zaitsev

DOI: http://dx.doi.org/10.12775/LLP.2016.016


The aim of the present paper is to introduce a system, where the epistemic state of an agent is represented truth-functionally. In order to obtain this system, we propose a four-valued logic, that we call the logic of rational agent, where the fact of knowing something is formalized at the level of valuations, without the explicit use of epistemic knowledge operator. On the basis of this semantics, a sound and complete system with two distinct truth-functional negations (an “ontological” and an “epistemic” one) is provided. These negations allow us to express the statements about knowing or not knowing something at the syntactic level. Moreover, such a system is applied to the analysis of knowability paradox. In particular, we show that the paradox is not derivable in terms of the logic of rational agent.


many-valued logics; generalized truth values; Church-Fitch’s paradox

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ISSN: 1425-3305 (print version)

ISSN: 2300-9802 (electronic version)

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