Theorem orc

Description: Introduction of a disjunct. Theorem *2.2 of WhiteheadRussell p. 104. (Contributed by NM, 30-Aug-1993)

	Ref	Expression
Assertion	orc	⊢ ( 𝜑 → ( 𝜑 ∨ 𝜓 ) )

Proof

Step	Hyp	Ref	Expression
1		pm2.24	⊢ ( 𝜑 → ( ¬ 𝜑 → 𝜓 ) )
2	1	orrd	⊢ ( 𝜑 → ( 𝜑 ∨ 𝜓 ) )