Combining Philosophers

All the ideas for Speussipus, Gerhard Gentzen and Alexius Meinong

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14 ideas

4. Formal Logic / E. Nonclassical Logics / 6. Free Logic
8250 So-called 'free logic' operates without existence assumptions [Meinong, by George/Van Evra]
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]
9. Objects / A. Existence of Objects / 2. Abstract Objects / c. Modern abstracta
8719 There can be impossible and contradictory objects, if they can have properties [Meinong, by Friend]
9. Objects / A. Existence of Objects / 3. Objects in Thought
8971 There are objects of which it is true that there are no such objects [Meinong]
8718 Meinong says an object need not exist, but must only have properties [Meinong, by Friend]
9. Objects / A. Existence of Objects / 4. Impossible objects
7756 Meinong said all objects of thought (even self-contradictions) have some sort of being [Meinong, by Lycan]
15781 The objects of knowledge are far more numerous than objects which exist [Meinong]
9. Objects / B. Unity of Objects / 2. Substance / c. Types of substance
594 Speusippus suggested underlying principles for every substance, and ended with a huge list [Speussipus, by Aristotle]
28. God / C. Attitudes to God / 5. Atheism
2632 Speusippus said things were governed by some animal force rather than the gods [Speussipus, by Cicero]