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Single Idea 21714

[filed under theme 6. Mathematics / C. Sources of Mathematics / 6. Logicism / b. Type theory ]

Full Idea

The original ramified theory of types ...furthern subdivides each of the types of the 'simple' theory according to the range of the bound variables used in the definition of each propositional function.

Gist of Idea

The ramified theory subdivides each type, according to the range of the variables

Source

Bernard Linsky (Russell's Metaphysical Logic [1999], 6)

Book Ref

Linsky,Bernard: 'Russell's Metaphysical Logic' [CSLI 1999], p.89


A Reaction

For a non-intiate like me it certainly sounds disappointing that such a bold and neat theory because a tangle of complications. Ramsey and Russell in the 1920s seem to have dropped the ramifications.


The 13 ideas from Bernard Linsky

Definite descriptions, unlike proper names, have a logical structure [Linsky,B]
Contextual definitions eliminate descriptions from contexts [Linsky,B]
'Impredictative' definitions fix a class in terms of the greater class to which it belongs [Linsky,B]
Reducibility says any impredicative function has an appropriate predicative replacement [Linsky,B]
Types are 'ramified' when there are further differences between the type of quantifier and its range [Linsky,B]
The ramified theory subdivides each type, according to the range of the variables [Linsky,B]
Did logicism fail, when Russell added three nonlogical axioms, to save mathematics? [Linsky,B]
For those who abandon logicism, standard set theory is a rival option [Linsky,B]
Extensionalism means what is true of a function is true of coextensive functions [Linsky,B]
Higher types are needed to distinguished intensional phenomena which are coextensive [Linsky,B]
The task of logicism was to define by logic the concepts 'number', 'successor' and '0' [Linsky,B]
Definite descriptions theory eliminates the King of France, but not the Queen of England [Linsky,B]
Construct properties as sets of objects, or say an object must be in the set to have the property [Linsky,B]