Theorem pm2.24

Description: Theorem *2.24 of WhiteheadRussell p. 104. Its associated inference is pm2.24i . Commuted form of pm2.21 . (Contributed by NM, 3-Jan-2005)

	Ref	Expression
Assertion	pm2.24	$$⊢\phi \to \left(\neg \phi \to \psi \right)$$

Proof

Step	Hyp	Ref	Expression
1		pm2.21	$$⊢\neg \phi \to \left(\phi \to \psi \right)$$
2	1	com12	$$⊢\phi \to \left(\neg \phi \to \psi \right)$$