more from A.George / D.J.Velleman

Single Idea 10126

[catalogued under 5. Theory of Logic / K. Features of Logics / 2. Consistency]

Full Idea

If there is a sentence such that both the sentence and its negation are theorems of a theory, then the theory is 'inconsistent'. Otherwise it is 'consistent'.

Gist of Idea

A 'consistent' theory cannot contain both a sentence and its negation


A.George / D.J.Velleman (Philosophies of Mathematics [2002], Ch.7)

Book Reference

George,A/Velleman D.J.: 'Philosophies of Mathematics' [Blackwell 2002], p.177