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Single Idea 7689

[filed under theme 4. Formal Logic / D. Modal Logic ML / 4. Alethic Modal Logic ]

Full Idea

The modal syntax and axiom systems of C.I.Lewis (1918) were formally interpreted by Kripke and Hintikka (c.1965) who, using Z-F set theory, worked out model set-theoretical semantics for modal logics and quantified modal logics.

Clarification

Z-F stands for Zermelo-Fraenkel

Gist of Idea

The modal logic of C.I.Lewis was only interpreted by Kripke and Hintikka in the 1960s

Source

Dale Jacquette (Ontology [2002], Ch. 2)

Book Ref

Jacquette,Dale: 'Ontology' [Acumen 2002], p.70


A Reaction

A historical note. The big question is always 'who cares?' - to which the answer seems to be 'lots of people', if they are interested in precision in discourse, in artificial intelligence, and maybe even in metaphysics. Possible worlds started here.


The 11 ideas with the same theme [inference from truths concerning necessity and possibility]:

There are three different deductions for actual terms, necessary terms and possible terms [Aristotle]
Modal logic is not an extensional language [Parsons,C]
For modality Lewis rejected boxes and diamonds, preferring worlds, and an index for the actual one [Lewis, by Stalnaker]
Metaphysical (alethic) modal logic concerns simple necessity and possibility (not physical, epistemic..) [Salmon,N]
The modal logic of C.I.Lewis was only interpreted by Kripke and Hintikka in the 1960s [Jacquette]
The main modal logics disagree over three key formulae [Yablo]
Modality affects content, because P→◊P is valid, but ◊P→P isn't [Fitting/Mendelsohn]
S4: 'poss that poss that p' implies 'poss that p'; S5: 'poss that nec that p' implies 'nec that p' [Orenstein]
Possible worlds logics use true-in-a-world rather than true [Girle]
Modal logic has four basic modal negation equivalences [Girle]
Modal logics were studied in terms of axioms, but now possible worlds semantics is added [Girle]