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Single Idea 10928

[filed under theme 4. Formal Logic / D. Modal Logic ML / 1. Modal Logic ]

Full Idea

Perhaps there is no objection to quantifying into modal contexts as long as the values of any variables thus quantified are limited to intensional objects, but they also lead to disturbing examples.

Clarification

'Intensional' objects are in thought rather than in reality

Gist of Idea

Maybe we can quantify modally if the objects are intensional, but it seems unlikely

Source

Willard Quine (Reference and Modality [1953], §3)

Book Ref

Quine,Willard: 'From a Logical Point of View' [Harper and Row 1963], p.152

A Reaction

[Quine goes on to give his examples] I take it that possibilities are features of actual reality, not merely objects of thought. The problem is that they are harder to know than actual objects.

The 18 ideas with the same theme [general ideas about the nature of modal logic]:

9728 Modal Square 1: □P and ¬◊¬P are 'contraries' of □¬P and ¬◊P [Aristotle, by Fitting/Mendelsohn]
9729 Modal Square 2: ¬□¬P and ◊P are 'subcontraries' of ¬□P and ◊¬P [Aristotle, by Fitting/Mendelsohn]
9730 Modal Square 3: □P and ¬◊¬P are 'contradictories' of ¬□P and ◊¬P [Aristotle, by Fitting/Mendelsohn]
9731 Modal Square 4: □¬P and ¬◊P are 'contradictories' of ¬□¬P and ◊P [Aristotle, by Fitting/Mendelsohn]
9732 Modal Square 5: □P and ¬◊¬P are 'subalternatives' of ¬□¬P and ◊P [Aristotle, by Fitting/Mendelsohn]
9733 Modal Square 6: □¬P and ¬◊P are 'subalternatives' of ¬□P and ◊¬P [Aristotle, by Fitting/Mendelsohn]
5745 Quine says quantified modal logic creates nonsense, bad ontology, and false essentialism [Melia on Quine]
13591 Quantified modal logic collapses if essence is withdrawn [Quine]
10928 Maybe we can quantify modally if the objects are intensional, but it seems unlikely [Quine]
16951 It was realised that possible worlds covered all modal logics, if they had a structure [Dummett]
10163 Propositional modal logic has been proved to be complete [Kripke, by Feferman/Feferman]
10559 Kripke's modal semantics presupposes certain facts about possible worlds [Kripke, by Zalta]
16985 Possible worlds allowed the application of set-theoretic models to modal logic [Kripke]
15163 The interest of quantified modal logic is its metaphysical necessity and essentialism [Soames]
10206 Modal operators are usually treated as quantifiers [Shapiro]
9924 Modal logic gives an account of metalogical possibility, not metaphysical possibility [Burgess/Rosen]
5744 First-order predicate calculus is extensional logic, but quantified modal logic is intensional (hence dubious) [Melia]
19209 Simple Quantified Modal Logc doesn't work, because the Converse Barcan is a theorem [Merricks]