Combining Texts

All the ideas for 'works', 'Types and Ontology' and 'Investigations into Logical Deduction'

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4 ideas

4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / a. Axioms for sets

9565	Zermelo made 'set' and 'member' undefined axioms [Zermelo, by Chihara]

3339	For Zermelo's set theory the empty set is zero and the successor of each number is its unit set [Zermelo, by Blackburn]

5. Theory of Logic / H. Proof Systems / 4. Natural Deduction

13832

Natural deduction shows the heart of reasoning (and sequent calculus is just a tool) [Gentzen, by Hacking]

7. Existence / E. Categories / 1. Categories

13127

Categories can't overlap; they are either disjoint, or inclusive [Sommers, by Westerhoff]