Theorem pm2.24 551

Description: Theorem *2.24 of [WhiteheadRussell] p. 104. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm2.24	⊢ (𝜑 → (¬ 𝜑 → 𝜓))

Proof of Theorem pm2.24

Step	Hyp	Ref	Expression
1		pm2.21 547	. 2 ⊢ (¬ 𝜑 → (𝜑 → 𝜓))
2	1	com12 27	1 ⊢ (𝜑 → (¬ 𝜑 → 𝜓))

Syntax hints:  ¬ wn 3   → wi 4

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-in2 545

This theorem is referenced by:  pm2.24d  552  pm2.53  641  pm2.82  725  pm4.81dc  814  dedlema  876  alexim  1536  sotritric  4061  ltxrlt  7085  zltnle  8291  elfzonlteqm1  9066  qltnle  9101