Combining Philosophers

All the ideas for Karl Weierstrass, GE Hughes/M Cresswell and Helen Cartwright

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7 ideas

4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / b. Terminology of PL

9540	A 'value-assignment' (V) is when to each variable in the set V assigns either the value 1 or the value 0 [Hughes/Cresswell]

4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / d. Basic theorems of PL

9541	The Law of Transposition says (P→Q) → (¬Q→¬P) [Hughes/Cresswell]

4. Formal Logic / B. Propositional Logic PL / 4. Soundness of PL

9543	The rules preserve validity from the axioms, so no thesis negates any other thesis [Hughes/Cresswell]

5. Theory of Logic / F. Referring in Logic / 1. Naming / d. Singular terms

10670

A 'singulariser' converts a plural like 'number of' to a syntactically neutral form [Cartwright,H, by Hossack]

5. Theory of Logic / K. Features of Logics / 4. Completeness

9544	A system is 'weakly' complete if all wffs are derivable, and 'strongly' if theses are maximised [Hughes/Cresswell]

6. Mathematics / A. Nature of Mathematics / 5. The Infinite / k. Infinitesimals

18086

Weierstrass eliminated talk of infinitesimals [Weierstrass, by Kitcher]

6. Mathematics / A. Nature of Mathematics / 5. The Infinite / l. Limits

18092

Weierstrass made limits central, but the existence of limits still needed to be proved [Weierstrass, by Bostock]