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	⊢ ( ( 𝜑 ∨ 𝜑 ) → 𝜑 )

Proof

Step	Hyp	Ref	Expression
1		id	⊢ ( 𝜑 → 𝜑 )
2	1 1	jaoi	⊢ ( ( 𝜑 ∨ 𝜑 ) → 𝜑 )