Combining Texts

All the ideas for 'The Identity of Indiscernibles', 'In Praed.' and 'Grundgesetze der Arithmetik 1 (Basic Laws)'

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14 ideas

4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / j. Axiom of Choice IX
The Axiom of Choice needs a criterion of choice [Black]
5. Theory of Logic / F. Referring in Logic / 2. Descriptions / b. Definite descriptions
Frege considered definite descriptions to be genuine singular terms [Frege, by Fitting/Mendelsohn]
5. Theory of Logic / G. Quantification / 4. Substitutional Quantification
Contradiction arises from Frege's substitutional account of second-order quantification [Dummett on Frege]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / g. Real numbers
Real numbers are ratios of quantities, such as lengths or masses [Frege]
6. Mathematics / B. Foundations for Mathematics / 1. Foundations for Mathematics
We can't prove everything, but we can spell out the unproved, so that foundations are clear [Frege]
6. Mathematics / B. Foundations for Mathematics / 5. Definitions of Number / c. Fregean numbers
Frege defined number in terms of extensions of concepts, but needed Basic Law V to explain extensions [Frege, by Hale/Wright]
Frege ignored Cantor's warning that a cardinal set is not just a concept-extension [Tait on Frege]
6. Mathematics / C. Sources of Mathematics / 6. Logicism / a. Early logicism
My Basic Law V is a law of pure logic [Frege]
9. Objects / A. Existence of Objects / 5. Individuation / b. Individuation by properties
Two things can only be distinguished by a distinct property or a distinct relation [Black]
9. Objects / B. Unity of Objects / 2. Substance / a. Substance
Substance is an intrinsic thing, so parts of substances can't also be intrinsic things [Duns Scotus]
9. Objects / F. Identity among Objects / 5. Self-Identity
The 'property' of self-identity is uselessly tautological [Black]
9. Objects / F. Identity among Objects / 7. Indiscernible Objects
If the universe just held two indiscernibles spheres, that refutes the Identity of Indiscernibles [Black]
18. Thought / D. Concepts / 3. Ontology of Concepts / c. Fregean concepts
A concept is a function mapping objects onto truth-values, if they fall under the concept [Frege, by Dummett]
Frege took the study of concepts to be part of logic [Frege, by Shapiro]