Journal of Philosophical Logic

, Volume 31, Issue 5, pp 387-414

First online:

Propositional Q-Logic

  • Stefan WölflAffiliated withDipartimento di Matematica Pura ed Applicata, Università degli Studi di Padova

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Topic of the paper is Q-logic – a logic of agency in its temporal and modal context. Q-logic may be considered as a basal logic of agency since the most important stit-operators discussed in the literature can be defined or axiomatized easily within its semantical and syntactical framework. Its basic agent dependent operator, the Q-operator (also known as Δ- or cstit-operator), which has been discussed independently by F. v. Kutschera and B. F. Chellas, is investigated here in respect of its relation to other temporal and modal operators. The main result of the paper, then, is a completeness result for a calculus of Q-logic with respect to a semantics defined on the tree-approach to agency as introduced and developed by, among others, F. v. Kutschera and N. D. Belnap.

agency branching histories completeness stit