Combining Philosophers

All the ideas for Archimedes, Fred Sommers and Dag Prawitz

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16 ideas

3. Truth / B. Truthmakers / 5. What Makes Truths / a. What makes truths
Truthmakers are facts 'of' a domain, not something 'in' the domain [Sommers]
4. Formal Logic / A. Syllogistic Logic / 3. Term Logic
'Predicable' terms come in charged pairs, with one the negation of the other [Sommers, by Engelbretsen]
Logic which maps ordinary reasoning must be transparent, and free of variables [Sommers]
5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
Logic is based on transitions between sentences [Prawitz]
5. Theory of Logic / B. Logical Consequence / 1. Logical Consequence
Logical consequence isn't a black box (Tarski's approach); we should explain how arguments work [Prawitz]
5. Theory of Logic / D. Assumptions for Logic / 4. Identity in Logic
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
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
Natural deduction introduction rules may represent 'definitions' of logical connectives [Prawitz]
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / c. not
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
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
In natural deduction, inferences are atomic steps involving just one logical constant [Prawitz]
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
Model theory looks at valid sentences and consequence, but not how we know these things [Prawitz]
6. Mathematics / B. Foundations for Mathematics / 3. Axioms for Geometry
Archimedes defined a straight line as the shortest distance between two points [Archimedes, by Leibniz]
7. Existence / D. Theories of Reality / 2. Realism
Unfortunately for realists, modern logic cannot say that some fact exists [Sommers]
7. Existence / E. Categories / 1. Categories
Categories can't overlap; they are either disjoint, or inclusive [Sommers, by Westerhoff]
19. Language / B. Reference / 1. Reference theories
In standard logic, names are the only way to refer [Sommers]