Combining Texts

All the ideas for 'works', 'Two Chief World Systems' and 'The iterative conception of Set'

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3 ideas

4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / h. Axiom of Replacement VII
Do the Replacement Axioms exceed the iterative conception of sets? [Boolos, by Maddy]
     Full Idea: For Boolos, the Replacement Axioms go beyond the iterative conception.
     From: report of George Boolos (The iterative conception of Set [1971]) by Penelope Maddy - Naturalism in Mathematics I.3
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.
27. Natural Reality / A. Classical Physics / 1. Mechanics / b. Laws of motion
Galileo mathematised movement, and revealed its invariable component - acceleration [Galileo, by Meillassoux]
     Full Idea: Galileo conceives of movement in mathematical terms. ...In doing so, he uncovered, beyond the variations of position and speed, the mathematical invariant of movement - that is to say, acceleration.
     From: report of Galileo Galilei (Two Chief World Systems [1632]) by Quentin Meillassoux - After Finitude; the necessity of contingency 5
     A reaction: That is a very nice advert for the mathematical physics which replaced the Aristotelian substantial forms. ...And yet, is acceleration some deep fact about nature, or a concept which is only needed if you insist on being mathematical?