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Full Idea
Belief that every valid argument is valid in virtue of form is a myth. ..Validity is a question of the impossibility of true premises and false conclusion for whatever reason, and some arguments are materially valid and the reason is not purely logical.
Gist of Idea
Not all arguments are valid because of form; validity is just true premises and false conclusion being impossible
Source
Stephen Read (Formal and Material Consequence [1994], 'Logic')
Book Ref
'Philosophy of Logic: an anthology', ed/tr. Jacquette,Dale [Blackwell 2002], p.245
A Reaction
An example of a non-logical reason is the transitive nature of 'taller than'. Conceptual connections are the usual example, as in 'it's red so it is coloured'. This seems to be a defence of the priority of semantic consequence in logic.
Related Idea
Idea 14182 If the logic of 'taller of' rests just on meaning, then logic may be the study of merely formal consequence [Read]
14188 | Not all arguments are valid because of form; validity is just true premises and false conclusion being impossible [Read] |
14187 | If logic is topic-neutral that means it delves into all subjects, rather than having a pure subject matter [Read] |
14182 | If the logic of 'taller of' rests just on meaning, then logic may be the study of merely formal consequence [Read] |
14184 | In modus ponens the 'if-then' premise contributes nothing if the conclusion follows anyway [Read] |
14186 | Logical connectives contain no information, but just record combination relations between facts [Read] |
14185 | Conditionals are just a shorthand for some proof, leaving out the details [Read] |
14183 | Maybe arguments are only valid when suppressed premises are all stated - but why? [Read] |