Open AccessSemantics for Counterpossibles
Author(s) -
Yale Weiss
Publication year - 2017
Publication title -
australasian journal of logic
Language(s) - English
Resource type - Journals
ISSN - 1448-5052
DOI - 10.26686/ajl.v14i4.4050
Subject(s) - counterfactual conditional , soundness , ceteris paribus , completeness (order theory) , semantics (computer science) , possible world , epistemology , object (grammar) , counterfactual thinking , computer science , mathematics , artificial intelligence , programming language , philosophy , mathematical analysis
The object of this paper is to examine two approaches to giving non-vacuous truth conditions for counterpossibles, counterfactuals with impossible antecedents. I first develop modifications of a Lewis-style sphere semantics with impossible worlds. I argue that this approach sanctions intuitively invalid inferences and is supported by philosophically problematic foundations. I then develop modifications of certain ceteris paribus conditional logics with impossible worlds. Tableaux are given for each of these in an appendix and soundness and completeness results are proved. While certain of the latter systems are shown to have similar problems to logics from the first approach, at least one relatively weak system appears to offer an adequate uniform semantics for counterpossibles and counterfactuals.