more on this theme | more from this text
Full Idea
The manifestation of the belief that a mode of inference is logically necessarily truth-preserving is the preparedness to employ that mode of inference in reasoning from any set of suppositions whatsoever.
Gist of Idea
The mark of logical necessity is deduction from any suppositions whatever
Source
Ian McFetridge (Logical Necessity: Some Issues [1986], §4)
Book Ref
-: 'Aristotelian Society' [], p.153
A Reaction
He rests this on the idea of 'cotenability' of the two sides of a counterfactual (in Mill, Goodman and Lewis). There seems, at first blush, to be a problem of the relevance of the presuppositions.
| 15083 | The fundamental case of logical necessity is the valid conclusion of an inference [McFetridge, by Hale] |
| 15084 | In the McFetridge view, logical necessity means a consequent must be true if the antecedent is [McFetridge, by Hale] |
| 12180 | Logical necessity requires that a valid argument be necessary [McFetridge] |
| 12181 | Traditionally, logical necessity is the strongest, and entails any other necessities [McFetridge] |
| 12183 | It is only logical necessity if there is absolutely no sense in which it could be false [McFetridge] |
| 12182 | We assert epistemic possibility without commitment to logical possibility [McFetridge] |
| 12184 | Logical necessity overrules all other necessities [McFetridge] |
| 12187 | Objectual modal realists believe in possible worlds; non-objectual ones rest it on the actual world [McFetridge] |
| 12186 | Modal realists hold that necessities and possibilities are part of the totality of facts [McFetridge] |
| 12192 | The mark of logical necessity is deduction from any suppositions whatever [McFetridge] |
| 18487 | We want to know what makes sentences true, rather than defining 'true' [McFetridge] |
| 18488 | We normally explain natural events by citing further facts [McFetridge] |