Combining Texts

Ideas for 'Thinking About Mathematics', 'On Fate ('De fato')' and 'Atomism'

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2 ideas

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 / 2. Excluded Middle
Intuitionists deny excluded middle, because it is committed to transcendent truth or objects [Shapiro]
     Full Idea: Intuitionists in mathematics deny excluded middle, because it is symptomatic of faith in the transcendent existence of mathematical objects and/or the truth of mathematical statements.
     From: Stewart Shapiro (Thinking About Mathematics [2000], 1.2)
     A reaction: There are other problems with excluded middle, such as vagueness, but on the whole I, as a card-carrying 'realist', am committed to the law of excluded middle.