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Ideas for 'works', 'Looking for Spinoza' and 'On Fate ('De fato')'

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5. Theory of Logic / D. Assumptions for Logic / 1. Bivalence
How can the not-true fail to be false, or the not-false fail to be true? [Cicero]
     Full Idea: How can something that is not true not be false, or how can something that is not false not be true?
     From: M. Tullius Cicero (On Fate ('De fato') [c.44 BCE], 16.38)
     A reaction: We must at least distinguish between whether the contrary thing is not actually true, or whether we are prepared to assert that it is not true. The disjunction may seem to be a false dichotomy. 'He isn't good' may not entail 'he is evil'.
5. Theory of Logic / D. Assumptions for Logic / 3. Contradiction
Contradiction is not a sign of falsity, nor lack of contradiction a sign of truth [Pascal]
     Full Idea: Contradiction is not a sign of falsity, nor the lack of contradiction a sign of truth.
     From: Blaise Pascal (works [1660]), quoted by A.George / D.J.Velleman - Philosophies of Mathematics Ch.6
     A reaction: [Quoted in Auden and Kronenberger's Book of Aphorisms] Presumably we would now say that contradiction is a purely formal, syntactic notion, and not a semantic one. If you hit a contradiction, something has certainly gone wrong.