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Ideas for 'Metaphysics: the logical approach', 'Is Mathematics purely Linguistic?' and 'On Second-Order Logic'

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6. Mathematics / A. Nature of Mathematics / 2. Geometry
3332 Greeks saw the science of proportion as the link between geometry and arithmetic [Benardete,JA]
     Full Idea: The Greeks saw the independent science of proportion as the link between geometry and arithmetic.
     From: José A. Benardete (Metaphysics: the logical approach [1989], Ch.15)
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / b. Types of number
3330 Negatives, rationals, irrationals and imaginaries are all postulated to solve baffling equations [Benardete,JA]
     Full Idea: The Negative numbers are postulated (magic word) to solve x=5-8, Rationals postulated to solve 2x=3, Irrationals for x-squared=2, and Imaginaries for x-squared=-1. (…and Zero for x=5-5) …and x/0 remains eternally open.
     From: José A. Benardete (Metaphysics: the logical approach [1989], Ch.14)
3337 Natural numbers are seen in terms of either their ordinality (Peano), or cardinality (set theory) [Benardete,JA]
     Full Idea: One approaches the natural numbers in terms of either their ordinality (Peano), or cardinality (set theory).
     From: José A. Benardete (Metaphysics: the logical approach [1989], Ch.17)
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / e. Peano arithmetic 2nd-order
10833 Many concepts can only be expressed by second-order logic [Boolos]
     Full Idea: The notions of infinity and countability can be characterized by second-order sentences, though not by first-order sentences (as compactness and Skolem-Löwenheim theorems show), .. as well as well-ordering, progression, ancestral and identity.
     From: George Boolos (On Second-Order Logic [1975], p.48)
6. Mathematics / C. Sources of Mathematics / 7. Formalism
21570 Numbers are just verbal conveniences, which can be analysed away [Russell]
     Full Idea: Numbers are nothing but a verbal convenience, and disappear when the propositions that seem to contain them are fully written out.
     From: Bertrand Russell (Is Mathematics purely Linguistic? [1952], p.301)
     A reaction: This is the culmination of the process which began with his 1905 theory of definite descriptions. The intervening step was Wittgenstein's purely formal account of the logical connectives.