Combining Texts
Ideas for
'Protagoras', 'Grundlagen der Arithmetik (Foundations)' and 'The Inference to the Best Explanation'
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6 ideas
4. Formal Logic / F. Set Theory ST / 3. Types of Set / b. Empty (Null) Set
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9157
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The null set is only defensible if it is the extension of an empty concept [Frege, by Burge]
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9835
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It is because a concept can be empty that there is such a thing as the empty class [Frege, by Dummett]
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4. Formal Logic / F. Set Theory ST / 3. Types of Set / e. Equivalence classes
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9854
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We can introduce new objects, as equivalence classes of objects already known [Frege, by Dummett]
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9883
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Frege introduced the standard device, of defining logical objects with equivalence classes [Frege, by Dummett]
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4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / f. Axiom of Infinity V
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18104
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Frege, unlike Russell, has infinite individuals because numbers are individuals [Frege, by Bostock]
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4. Formal Logic / F. Set Theory ST / 5. Conceptions of Set / c. Logical sets
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9834
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A class is, for Frege, the extension of a concept [Frege, by Dummett]
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