The Logic of Contingent Actuality

Current orthodoxy in modal logic and metaphysics has it that actuality is non-contingent in the following sense: for all p, if actually, p, then necessarily, actually, p. Call this thesis (Actuality) Necessitism and its negation (Actuality) Contingentism. Thus, according to Contingentism, there is a...

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Main Authors: Martin Glazier, Stephan Krämer
Format: Article
Language:English
Published: Michigan Publishing 2024-05-01
Series:Ergo, An Open Access Journal of Philosophy
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Online Access:https://journals.publishing.umich.edu/ergo/article/id/5713/
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author Martin Glazier
Stephan Krämer
author_facet Martin Glazier
Stephan Krämer
author_sort Martin Glazier
collection DOAJ
description Current orthodoxy in modal logic and metaphysics has it that actuality is non-contingent in the following sense: for all p, if actually, p, then necessarily, actually, p. Call this thesis (Actuality) Necessitism and its negation (Actuality) Contingentism. Thus, according to Contingentism, there is at least one proposition p which is actually true but which could have been actually false. In another paper, one of us (Glazier 2023) has recently defended Contingentism. The present paper explores the logic of actuality under Contingentism. After informally introducing Contingentism and outlining what we take to be the main motivations for accepting it, we consider how contingent actuality should be taken to be. We argue that the nature, or essence, of actuality imposes certain limits on the extent to which actuality could have been different, and these then inform our view of the logic of actuality. Turning to the formal study of the logic of contingent actuality, we specify a formal language and a possible world semantics for that language and distinguish a number of natural notions of validity and consequence to which it gives rise. We present axiomatizations of the different resulting logics and examine the variety of iterated modalities in our systems. We establish soundness and completeness results.
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spelling doaj-art-9908c4f31f844bb682ccc91b7ca07e052025-08-20T02:13:24ZengMichigan PublishingErgo, An Open Access Journal of Philosophy2330-40142024-05-0111010.3998/ergo.5713The Logic of Contingent ActualityMartin Glazier0Stephan Krämer1https://orcid.org/0000-0003-1783-8742Philosophy, University of HamburgPhilosophy, University of HamburgCurrent orthodoxy in modal logic and metaphysics has it that actuality is non-contingent in the following sense: for all p, if actually, p, then necessarily, actually, p. Call this thesis (Actuality) Necessitism and its negation (Actuality) Contingentism. Thus, according to Contingentism, there is at least one proposition p which is actually true but which could have been actually false. In another paper, one of us (Glazier 2023) has recently defended Contingentism. The present paper explores the logic of actuality under Contingentism. After informally introducing Contingentism and outlining what we take to be the main motivations for accepting it, we consider how contingent actuality should be taken to be. We argue that the nature, or essence, of actuality imposes certain limits on the extent to which actuality could have been different, and these then inform our view of the logic of actuality. Turning to the formal study of the logic of contingent actuality, we specify a formal language and a possible world semantics for that language and distinguish a number of natural notions of validity and consequence to which it gives rise. We present axiomatizations of the different resulting logics and examine the variety of iterated modalities in our systems. We establish soundness and completeness results.https://journals.publishing.umich.edu/ergo/article/id/5713/modal logicactualitycontingency
spellingShingle Martin Glazier
Stephan Krämer
The Logic of Contingent Actuality
Ergo, An Open Access Journal of Philosophy
modal logic
actuality
contingency
title The Logic of Contingent Actuality
title_full The Logic of Contingent Actuality
title_fullStr The Logic of Contingent Actuality
title_full_unstemmed The Logic of Contingent Actuality
title_short The Logic of Contingent Actuality
title_sort logic of contingent actuality
topic modal logic
actuality
contingency
url https://journals.publishing.umich.edu/ergo/article/id/5713/
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