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4. Formal Logic / F. Set Theory ST / 5. Conceptions of Set / c. Logical sets

[sets whose membership is defined by a concept]

5 ideas
A class is, for Frege, the extension of a concept [Dummett on Frege]
Frege proposed a realist concept of a set, as the extension of a predicate or concept or function [Benardete,JA on Frege]
Propositions about classes can be reduced to propositions about their defining functions [Russell]
Realisms like the full Comprehension Principle, that all good concepts determine sets [Read]
The 'logical' notion of class has some kind of definition or rule to characterise the class [Lavine]