Theorem pm1.2

Description: Axiom *1.2 of WhiteheadRussell p. 96, which they call "Taut". (Contributed by NM, 3-Jan-2005)

	Ref	Expression
Assertion	pm1.2	$$⊢\left(\phi \vee \phi \right)\to \phi$$

Proof

Step	Hyp	Ref	Expression
1		id	$$⊢\phi \to \phi$$
2	1 1	jaoi	$$⊢\left(\phi \vee \phi \right)\to \phi$$