Combining Texts

All the ideas for 'Aristotle and Descartes on Matter', 'Empiricism, Semantics and Ontology' and 'Alfred Tarski: life and logic'

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24 ideas

1. Philosophy / E. Nature of Metaphysics / 2. Possibility of Metaphysics
13939 No possible evidence could decide the reality of numbers, so it is a pseudo-question [Carnap]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / j. Axiom of Choice IX
10147 The Axiom of Choice is consistent with the other axioms of set theory [Feferman/Feferman]
10148 Axiom of Choice: a set exists which chooses just one element each of any set of sets [Feferman/Feferman]
10149 Platonist will accept the Axiom of Choice, but others want criteria of selection or definition [Feferman/Feferman]
10150 The Trichotomy Principle is equivalent to the Axiom of Choice [Feferman/Feferman]
10146 Cantor's theories needed the Axiom of Choice, but it has led to great controversy [Feferman/Feferman]
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
10158 A structure is a 'model' when the axioms are true. So which of the structures are models? [Feferman/Feferman]
10162 Tarski and Vaught established the equivalence relations between first-order structures [Feferman/Feferman]
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
10159 Löwenheim-Skolem Theorem, and Gödel's completeness of first-order logic, the earliest model theory [Feferman/Feferman]
10160 Löwenheim-Skolem says if the sentences are countable, so is the model [Feferman/Feferman]
5. Theory of Logic / K. Features of Logics / 4. Completeness
10161 If a sentence holds in every model of a theory, then it is logically derivable from the theory [Feferman/Feferman]
5. Theory of Logic / K. Features of Logics / 7. Decidability
10156 'Recursion theory' concerns what can be solved by computing machines [Feferman/Feferman]
10155 Both Principia Mathematica and Peano Arithmetic are undecidable [Feferman/Feferman]
6. Mathematics / C. Sources of Mathematics / 6. Logicism / a. Early logicism
13936 Questions about numbers are answered by analysis, and are analytic, and hence logically true [Carnap]
8748 Logical positivists incorporated geometry into logicism, saying axioms are just definitions [Carnap, by Shapiro]
7. Existence / A. Nature of Existence / 4. Abstract Existence
8960 Internal questions about abstractions are trivial, and external ones deeply problematic [Carnap, by Szabó]
7. Existence / D. Theories of Reality / 1. Ontologies
13933 Existence questions are 'internal' (within a framework) or 'external' (concerning the whole framework) [Carnap]
7. Existence / D. Theories of Reality / 3. Reality
13934 To be 'real' is to be an element of a system, so we cannot ask reality questions about the system itself [Carnap]
7. Existence / D. Theories of Reality / 11. Ontological Commitment / a. Ontological commitment
13938 A linguistic framework involves commitment to entities, so only commitment to the framework is in question [Carnap]
9. Objects / A. Existence of Objects / 6. Nihilism about Objects
13935 We only accept 'things' within a language with formation, testing and acceptance rules [Carnap]
12. Knowledge Sources / D. Empiricism / 1. Empiricism
13932 Empiricists tend to reject abstract entities, and to feel sympathy with nominalism [Carnap]
12. Knowledge Sources / D. Empiricism / 3. Pragmatism
13937 New linguistic claims about entities are not true or false, but just expedient, fruitful or successful [Carnap]
14. Science / B. Scientific Theories / 3. Instrumentalism
13940 All linguistic forms in science are merely judged by their efficiency as instruments [Carnap]
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / b. Prime matter
19399 Prime matter is nothing when it is at rest [Leibniz]