Combining Philosophers

All the ideas for Gorgias, Gerhard Gentzen and Peter (Pyotr) Kropotkin

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10 ideas

5. Theory of Logic / A. Overview of Logic / 2. History of Logic

11022

Gentzen introduced a natural deduction calculus (NK) in 1934 [Gentzen, by Read]

5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives

11065

The inferential role of a logical constant constitutes its meaning [Gentzen, by Hanna]

11023

The logical connectives are 'defined' by their introduction rules [Gentzen]

11213

Each logical symbol has an 'introduction' rule to define it, and hence an 'elimination' rule [Gentzen]

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]

6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / g. Incompleteness of Arithmetic

10067

Gentzen proved the consistency of arithmetic from assumptions beyond arithmetic [Gentzen, by Musgrave]

7. Existence / A. Nature of Existence / 3. Being / d. Non-being

18933

Not-Being obviously doesn't exist, and the five modes of Being are all impossible [Gorgias, by Diog. Laertius]

19. Language / F. Communication / 1. Rhetoric

5864	Destroy seriousness with laughter, and laughter with seriousness [Gorgias]

9866	Gorgias says rhetoric is the best of arts, because it enslaves without using force [Gorgias, by Plato]

25. Social Practice / B. Equalities / 1. Grounds of equality

20486

Only liberty, equality and sympathy can stand up to anti-social people [Kropotkin]