Combining Philosophers

All the ideas for Douglas Lackey, Hilbert,D/Ackermann,W and James Baillie

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4 ideas

4. Formal Logic / C. Predicate Calculus PC / 1. Predicate Calculus PC

17750

The first clear proof of the consistency of the first order predicate logic was in 1928 [Hilbert/Ackermann, by Walicki]

5. Theory of Logic / D. Assumptions for Logic / 4. Identity in Logic

3299	In logic identity involves reflexivity (x=x), symmetry (if x=y, then y=x) and transitivity (if x=y and y=z, then x=z) [Baillie]

5. Theory of Logic / L. Paradox / 5. Paradoxes in Set Theory / b. Cantor's paradox

21554

Sets always exceed terms, so all the sets must exceed all the sets [Lackey]

5. Theory of Logic / L. Paradox / 5. Paradoxes in Set Theory / c. Burali-Forti's paradox

21553

It seems that the ordinal number of all the ordinals must be bigger than itself [Lackey]