Combining Philosophers

All the ideas for H.Putnam/P.Oppenheim, Fred Sommers and Gerhard Gentzen

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17 ideas

3. Truth / B. Truthmakers / 5. What Makes Truths / a. What makes truths
18901 Truthmakers are facts 'of' a domain, not something 'in' the domain [Sommers]
4. Formal Logic / A. Syllogistic Logic / 3. Term Logic
18904 'Predicable' terms come in charged pairs, with one the negation of the other [Sommers, by Engelbretsen]
18895 Logic which maps ordinary reasoning must be transparent, and free of variables [Sommers]
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 / D. Assumptions for Logic / 4. Identity in Logic
18897 Predicate logic has to spell out that its identity relation '=' is an equivalent relation [Sommers]
5. Theory of Logic / E. Structures of Logic / 1. Logical Form
18893 Translating into quantificational idiom offers no clues as to how ordinary thinkers reason [Sommers]
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 / E. Structures of Logic / 2. Logical Connectives / c. not
18903 Sommers promotes the old idea that negation basically refers to terms [Sommers, by Engelbretsen]
5. Theory of Logic / E. Structures of Logic / 7. Predicates in Logic
18894 Predicates form a hierarchy, from the most general, down to names at the bottom [Sommers]
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 / D. Theories of Reality / 2. Realism
18900 Unfortunately for realists, modern logic cannot say that some fact exists [Sommers]
7. Existence / E. Categories / 1. Categories
13127 Categories can't overlap; they are either disjoint, or inclusive [Sommers, by Westerhoff]
14. Science / D. Explanation / 2. Types of Explanation / j. Explanations by reduction
20653 Six reduction levels: groups, lives, cells, molecules, atoms, particles [Putnam/Oppenheim, by Watson]
19. Language / B. Reference / 1. Reference theories
18898 In standard logic, names are the only way to refer [Sommers]