Modal Logic¶
Chellas, B. F. (1980). Modal Logic: An Introduction. Cambridge University Press.
Cited by¶
1 citation across 1 artifact.
Each citation links to the sentence it supports in the citing article.
Primes¶
- Modal Reasoning
- It separates the actual point from a field of alternatives, attaches a quantifier (universal for necessity, existential for possibility) to an inner proposition, and reads off a verdict relative to whichever alternatives the accessibility relation admits.
This sourceCanonical model-theoretic treatment of modal logic: shows how an operator quantifying an inner proposition over accessibility-admitted alternatives yields all/some/none verdicts, and how frame conditions (reflexive, transitive, Euclidean) define distinct systems (T, S4, S5) by compressing alternatives into operator-plus-relation.
Supported in partVerified against the publisher's abstract
The abstract confirms Chellas 1980 is a systematic textbook on modal logic, but it does not state the quantifier-over-accessibility mechanism; the claim is only partly supported.
“A textbook on modal logic, intended for readers already acquainted with the elements of formal logic, containing nearly 500 exercises. Chellas provides a systematic introduction to the principal ideas and results in contemporary treatments of modality, including theorems on completeness and decidability. Illustrative chapters focus on deontic logic and conditionality.”
- It separates the actual point from a field of alternatives, attaches a quantifier (universal for necessity, existential for possibility) to an inner proposition, and reads off a verdict relative to whichever alternatives the accessibility relation admits.
Verification¶
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