more from E.J. Lemmon

### Single Idea 13903

#### [catalogued under 4. Formal Logic / C. Predicate Calculus PC / 2. Tools of Predicate Calculus / c. Derivations rules of PC]

Full Idea

The elimination rule for the universal quantifier concerns the use of a universal proposition as a premiss to establish some conclusion, whilst the introduction rule concerns what is required by way of a premiss for a universal proposition as conclusion.

Gist of Idea

Universal elimination if you start with the universal, introduction if you want to end with it

Source

E.J. Lemmon (Beginning Logic [1965], 3.2)

Book Reference

Lemmon,E.J.: 'Beginning Logic' [Nelson 1979], p.104

A Reaction

So if you start with the universal, you need to eliminate it, and if you start without it you need to introduce it.