Single Idea 11012

[catalogued under 7. Existence / D. Theories of Reality / 10. Vagueness / f. Supervaluation for vagueness]

Full Idea

A 'supervaluation' says a proposition is true if it is true in all classical extensions of the original partial valuation. Thus 'A or not-A' has no valuation for an empty name, but if 'extended' to make A true or not-true, not-A always has opposite value.

Gist of Idea

A 'supervaluation' gives a proposition consistent truth-value for classical assignments

Source

Stephen Read (Thinking About Logic [1995], Ch.5)

Book Reference

Read,Stephen: 'Thinking About Logic' [OUP 1995], p.140


A Reaction

Makes you wonder how you can justify the extension. It can't just be for the convenience of logicians. You could hardly 'extend' T and F into quantum uncertainties.