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Single Idea 12194

[filed under theme 5. Theory of Logic / D. Assumptions for Logic / 3. Contradiction ]

Full Idea

Overt contradictions include formal contradictions of form 'B and not B', but I also take them to include 'This is red all over and green all over' and 'This is red and not coloured'.

Gist of Idea

Contradictions include 'This is red and not coloured', as well as the formal 'B and not-B'

Source

Ian Rumfitt (Logical Necessity [2010], Intro)

Book Ref

'Modality', ed/tr. Hale,B/Hoffman,A [OUP 2010], p.36


The 11 ideas from 'Logical Necessity'

A distinctive type of necessity is found in logical consequence [Rumfitt, by Hale/Hoffmann,A]
Logical necessity is when 'necessarily A' implies 'not-A is contradictory' [Rumfitt]
Contradictions include 'This is red and not coloured', as well as the formal 'B and not-B' [Rumfitt]
Soundness in argument varies with context, and may be achieved very informally indeed [Rumfitt]
Geometrical axioms in logic are nowadays replaced by inference rules (which imply the logical truths) [Rumfitt]
There is a modal element in consequence, in assessing reasoning from suppositions [Rumfitt]
We reject deductions by bad consequence, so logical consequence can't be deduction [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]
If a world is a fully determinate way things could have been, can anyone consider such a thing? [Rumfitt]
The logic of metaphysical necessity is S5 [Rumfitt]