more from Jennifer Fisher

### Single Idea 8943

#### [catalogued under 4. Formal Logic / E. Nonclassical Logics / 3. Many-Valued Logic]

Full Idea

In three-valued logic (L3), neither the law of excluded middle (p or not-p), nor the law of non-contradiction (not(p and not-p)) will be tautologies. If p has the value 'indeterminate' then so will not-p.

Gist of Idea

Three-valued logic says excluded middle and non-contradition are not tautologies

Source

Jennifer Fisher (On the Philosophy of Logic [2008], 07.I)

Book Reference

Fisher,Jennifer: 'On the Philosophy of Logic' [Thomson Wadsworth 2008], p.95

A Reaction

I quite accept that the world is full of indeterminate propositions, and that excluded middle and non-contradiction can sometimes be uncertain, but I am reluctant to accept that what is being offered here should be called 'logic'.