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Metamath Proof Explorer

Theorem pm2.1

Description: Theorem *2.1 of WhiteheadRussell p. 101. (Contributed by NM, 3-Jan-2005) (Proof shortened by Wolf Lammen, 23-Nov-2012)

		Ref	Expression
	Assertion	pm2.1	$⊢ (\neg φ \lor φ)$

Step	Hyp	Ref	Expression
1		id	$⊢ φ \to φ$
2	1	imori	$⊢ (\neg φ \lor φ)$