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Logical possibility

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Title: Logical possibility  
Author: World Heritage Encyclopedia
Language: English
Subject: Subjunctive possibility, Modal logic, Modal operator, History of logic, Feasibility
Collection: Modal Logic, Possibility
Publisher: World Heritage Encyclopedia

Logical possibility

A logically possible proposition is one which is consistent with the axioms of the logical system in which the proposition is made.[1] In other words, the logical possibility of a proposition will depend on the system of logic being used, rather than violation of any single rule. Some systems of logic tolerate inconsistent propositions or even true contradictions, while other logical systems have truth-value gaps instead of a binary of such values.


With this understanding of logical possibility in mind, other logical modalities may be defined in terms of it: a proposition is logically necessary if it is not logically possible for it to be false within some system of logic, logically impossible if it is not logically possible for it to be true in a system of logic, and logically contingent if it is logically possible for it to be true and logically possible for it to be false in some system of logic. Logical possibility can be further distinguished from metaphysical possibility, as the former refers to what is permissible in a system of logic, while the latter concerns what can be true at (or exist in) some possible world. Given the aforementioned description of logical possibility, some propositions can be logically possible (in a system of logic) and yet metaphysically impossible, or even logically impossible (in a system of logic) and yet be true of the world.

See also


  1. ^ Vaidya, Anand. "The Epistemology of Modality". Stanford Encyclopedia of Philosophy. Stanford Encyclopedia of Philosophy. Retrieved 10/10/205. 

External links

  • Do Modal Claims Imply the Existence of Possible Worlds?, paper criticizing David Lewis' theory of possibility.
