more from E.J. Lemmon

### Single Idea 13908

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

Full Idea

Univ Elim UE - if everything is F, then something is F; Univ Intro UI - if an arbitrary thing is F, everything is F; Exist Intro EI - if an arbitrary thing is F, something is F; Exist Elim EE - if a proof needed an object, there is one.

Gist of Idea

UE all-to-one; UI one-to-all; EI arbitrary-to-one; EE proof-to-one

Source

E.J. Lemmon (Beginning Logic [1965], 3.3)

Book Reference

Lemmon,E.J.: 'Beginning Logic' [Nelson 1979], p.111

A Reaction

[My summary of Lemmon's four main rules for predicate calculus] This is the natural deduction approach, of trying to present the logic entirely in terms of introduction and elimination rules. See Bostock on that.