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Ideas for 'fragments/reports', 'Response to David Armstrong' and 'Logical Necessity'

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4 ideas

10. Modality / A. Necessity / 3. Types of Necessity
A distinctive type of necessity is found in logical consequence [Rumfitt, by Hale/Hoffmann,A]
     Full Idea: Rumfitt argues that there is a distinctive notion of necessity implicated in the notion of logical consequence.
     From: report of Ian Rumfitt (Logical Necessity [2010]) by Bob Hale/ Aviv Hoffmann - Introduction to 'Modality' 2
10. Modality / A. Necessity / 6. Logical Necessity
Logical necessity is when 'necessarily A' implies 'not-A is contradictory' [Rumfitt]
     Full Idea: By the notion of 'logical necessity' I mean that there is a sense of 'necessary' for which 'It is necessary that A' implies and is implied by 'It is logically contradictory that not A'. ...From this, logical necessity is implicated in logical consequence.
     From: Ian Rumfitt (Logical Necessity [2010], Intro)
     A reaction: Rumfitt expresses a commitment to classical logic at this point. We will need to be quite sure what we mean by 'contradiction', which will need a clear notion of 'truth'....
A logically necessary statement need not be a priori, as it could be unknowable [Rumfitt]
     Full Idea: There is no reason to suppose that any statement that is logically necessary (in the present sense) is knowable a priori. ..If a statement is logically necessary, its negation will yield a contradiction, but that does not imply that someone could know it.
     From: Ian Rumfitt (Logical Necessity [2010], §2)
     A reaction: This remark is aimed at Dorothy Edgington, who holds the opposite view. Rumfitt largely defends McFetridge's view (q.v.).
Narrow non-modal logical necessity may be metaphysical, but real logical necessity is not [Rumfitt]
     Full Idea: While Fine suggests defining a narrow notion of logical necessity in terms of metaphysical necessity by 'restriction' (to logical truths that can be defined in non-modal terms), this seems unpromising for broad logical necessity, which is modal.
     From: Ian Rumfitt (Logical Necessity [2010], §2)
     A reaction: [compressed] He cites Kit Fine 2002. Rumfitt glosses the non-modal definitions as purely formal. The metaphysics lurks somewhere in the proof.