more from Herbert B. Enderton

### Single Idea 9719

#### [catalogued under 5. Theory of Logic / K. Features of Logics / 3. Soundness]

Full Idea

If every proof-theoretically valid inference is semantically valid (so that |- entails |=), the proof theory is said to be 'sound'.

Gist of Idea

A proof theory is 'sound' if its valid inferences entail semantic validity

Source

Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], 1.1.7)

Book Reference

Enderton,Herbert B.: 'A Mathematical Introduction to Logic' [Academic Press 2001], p.2