Combining Texts

Ideas for 'Axiomatic Theories of Truth (2005 ver)', 'The Philosophy of Mathematics' and 'On Fate ('De fato')'

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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 reject excluded middle, not for a third value, but for possibility of proof [Dummett]
     Full Idea: It must not be concluded from the rejection of excluded middle that intuitionistic logic operates with three values: true, false, and neither true nor false. It does not make use of true and false, but only with a construction being a proof.
     From: Michael Dummett (The Philosophy of Mathematics [1998], 8.1)
     A reaction: This just sounds like verificationism to me, with all its problems. It seems to make speculative statements meaningless, which can't be right. Realism has lots of propositions which are assumed to be true or false, but also unknowable.