13886
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Later Frege held that definitions must fix a function's value for every possible argument [Frege, by Wright,C]
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Full Idea:
Frege later became fastidious about definitions, and demanded that they must provide for every possible case, and that no function is properly determined unless its value is fixed for every conceivable object as argument.
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From:
report of Gottlob Frege (Grundgesetze der Arithmetik 2 (Basic Laws) [1903]) by Crispin Wright - Frege's Concept of Numbers as Objects 3.xiv
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A reaction:
Presumably definitions come in degrees of completeness, but it seems harsh to describe a desire for the perfect definition as 'fastidious', especially if we are talking about mathematics, rather than defining 'happiness'.
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9845
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We can't define a word by defining an expression containing it, as the remaining parts are a problem [Frege]
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Full Idea:
Given the reference (bedeutung) of an expression and a part of it, obviously the reference of the remaining part is not always determined. So we may not define a symbol or word by defining an expression in which it occurs, whose remaining parts are known
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From:
Gottlob Frege (Grundgesetze der Arithmetik 2 (Basic Laws) [1903], §66)
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A reaction:
Dummett cites this as Frege's rejection of contextual definitions, which he had employed in the Grundlagen. I take it not so much that they are wrong, as that Frege decided to set the bar a bit higher.
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9886
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Cardinals say how many, and reals give measurements compared to a unit quantity [Frege]
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Full Idea:
The cardinals and the reals are completely disjoint domains. The cardinal numbers answer the question 'How many objects of a given kind are there?', but the real numbers are for measurement, saying how large a quantity is compared to a unit quantity.
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From:
Gottlob Frege (Grundgesetze der Arithmetik 2 (Basic Laws) [1903], §157), quoted by Michael Dummett - Frege philosophy of mathematics Ch.19
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A reaction:
We might say that cardinals are digital and reals are analogue. Frege is unusual in totally separating them. They map onto one another, after all. Cardinals look like special cases of reals. Reals are dreams about the gaps between cardinals.
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9887
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Formalism misunderstands applications, metatheory, and infinity [Frege, by Dummett]
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Full Idea:
Frege's three main objections to radical formalism are that it cannot account for the application of mathematics, that it confuses a formal theory with its metatheory, and it cannot explain an infinite sequence.
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From:
report of Gottlob Frege (Grundgesetze der Arithmetik 2 (Basic Laws) [1903], §86-137) by Michael Dummett - Frege philosophy of mathematics
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A reaction:
The application is because we don't design maths randomly, but to be useful. The third objection might be dealt with by potential infinities (from formal rules). The second objection sounds promising.
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19347
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Substance needs independence, unity, and stability (for individuation); also it is a subject, for predicates [Perkins]
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Full Idea:
For individuation, substance needs three properties: independence, to separate it from other things; unity, to call it one thing, rather than an aggregate; and permanence or stability over time. Its other role is as subject for predicates.
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From:
Franklin Perkins (Leibniz: Guide for the Perplexed [2007], 3.1)
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A reaction:
Perkins is describing the Aristotelian view, which is taken up by Leibniz. 'Substance' is not a controversial idea, if we see that it only means that the world is full of 'things'. It is an unusual philosopher wholly totally denies that.
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11846
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If we abstract the difference between two houses, they don't become the same house [Frege]
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Full Idea:
If abstracting from the difference between my house and my neighbour's, I were to regard both houses as mine, the defect of the abstraction would soon be made clear. It may, though, be possible to obtain a concept by means of abstraction...
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From:
Gottlob Frege (Grundgesetze der Arithmetik 2 (Basic Laws) [1903], §99)
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A reaction:
Note the important concession at the end, which shows Frege could never deny the abstraction process, despite all the modern protests by Geach and Dummett that he totally rejected it.
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20544
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Berlin distinguishes 'negative' and 'positive' liberty, and rejects the latter [Berlin, by Swift]
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Full Idea:
Isaiah Berlin draws a famous distinction between 'negative' and 'positive' concepts of liberty, and argues that the latter should be seen as a wrong turning (because totalitarian regimes have invoked it).
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From:
report of Isaiah Berlin (Two Concepts of Liberty [1958]) by Adam Swift - Political Philosophy (3rd ed) 2 'Intro'
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A reaction:
Swift argues against him, saying that positive liberty is not a single concept (it's three), and has aspects that should be defended. I think I'm with Swift on that. Is religious freedom a freedom 'from' something, or a freedom 'to do' something?
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