Definition:Inconsistent (Logic)

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Definition

Let $\LL$ be a logical language.

Let $\mathscr P$ be a proof system for $\LL$.


A collection $\FF$ of logical formulas is inconsistent for $\mathscr P$ if and only if:

For every logical formula $\phi$, $\FF \vdash_{\mathscr P} \phi$.

That is, every logical formula $\phi$ is a provable consequence of $\FF$.


This article is complete as far as it goes, but it could do with expansion.
In particular: Include a variant comparable to Definition:Consistent (Logic)/Set of Formulas/Propositional Logic
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Also known as

Inconsistent collections of logical formulas are often called contradictory.

Likewise, a logical formula which is inconsistent by itself is often called a contradiction.

Since these terms are also often used to describe unsatisfiability in the context of a formal semantics, they are discouraged as synonyms of inconsistent on $\mathsf{Pr} \infty \mathsf{fWiki}$.


Also see


Sources

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