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10. Modality / A. Necessity / 6. Logical Necessity

[necessity because of logic or definitions]

40 ideas
A thing has a feature necessarily if its denial brings a contradiction [Aristotle]
Reasoning is when some results follow necessarily from certain claims [Aristotle]
Some facts about experience feel like logical necessities [Russell]
Frege moved Kant's question about a priori synthetic to 'how is logical certainty possible?' [Quine]
Contrary to some claims, Quine does not deny logical necessity [Quine, by McFetridge]
Logical necessity is grounded in the logical form of a statement [Harré/Madden]
The idea that anything which can be proved is necessary has a problem with empty names [Bostock]
The fundamental case of logical necessity is the valid conclusion of an inference [McFetridge, by Hale]
In the McFetridge view, logical necessity means a consequent must be true if the antecedent is [McFetridge, by Hale]
Traditionally, logical necessity is the strongest, and entails any other necessities [McFetridge]
Logical necessity requires that a valid argument be necessary [McFetridge]
It is only logical necessity if there is absolutely no sense in which it could be false [McFetridge]
Logical necessity overrules all other necessities [McFetridge]
The mark of logical necessity is deduction from any suppositions whatever [McFetridge]
Logical necessity involves a decision about usage, and is non-realist and non-cognitive [Wright,C, by McFetridge]
Logical necessity is free of constraints, and may accommodate all of S5 logic [Salmon,N]
Entailment does not result from mutual necessity; mutual necessity ensures entailment [Jubien]
Logical necessity is epistemic necessity, which is the old notion of a priori [Edgington, by McFetridge]
Logical modalities may be acceptable, because they are reducible to satisfaction in models [Shapiro]
Logical necessity has two sides - validity and demonstrability - which coincide in classical logic [Burgess]
General consensus is S5 for logical modality of validity, and S4 for proof [Burgess]
Broadly logical necessity (i.e. not necessarily formal logical necessity) is an epistemic notion [Edgington]
An argument is only valid if it is epistemically (a priori) necessary [Edgington]
Logical necessity can be 'strict' (laws), or 'narrow' (laws and definitions), or 'broad' (all logical worlds) [Lowe]
Explain logical necessity by logical consequence, or the other way around? [Correia]
'Broadly' logical necessities are derived (in a structure) entirely from the concepts [Hale]
Logical necessities are true in virtue of the nature of all logical concepts [Hale]
Logical truths must be necessary if anything is [Sider]
Logical necessity is something which is true, no matter what else is the case [Hale]
Maybe each type of logic has its own necessity, gradually becoming broader [Hale]
Something may be necessary because of logic, but is that therefore a special sort of necessity? [Rosen]
Logical necessitation is not a kind of necessity; George Orwell not being Eric Blair is not a real possibility [Bird]
Wittgenstein's plan to show there is only logical necessity failed, because of colours [MacBride]
Logical necessity is truth in all logically possible worlds, because of laws and concepts [Hanna]
The metaphysically and logically possible worlds are the same, so they are the same strength [Bennett,K]
Logical possibility needs the concepts of the proposition to be adequate [Boulter]
S5 is the logic of logical necessity [Rumfitt]
Logical necessity is when 'necessarily A' implies 'not-A is contradictory' [Rumfitt]
A logically necessary statement need not be a priori, as it could be unknowable [Rumfitt]
Narrow non-modal logical necessity may be metaphysical, but real logical necessity is not [Rumfitt]