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Full Idea
The higher types are needed for intensional phenomena, cases where the same class is picked out by distinct propositional functions.
Gist of Idea
Higher types are needed to distinguished intensional phenomena which are coextensive
Source
Bernard Linsky (Russell's Metaphysical Logic [1999], 6.4)
Book Ref
Linsky,Bernard: 'Russell's Metaphysical Logic' [CSLI 1999], p.101
A Reaction
I take it that in this way 'x is renate' can be distinguished from 'x is cordate', a task nowadays performed by possible worlds.
| 21704 | 'Impredictative' definitions fix a class in terms of the greater class to which it belongs [Linsky,B] |
| 21705 | Reducibility says any impredicative function has an appropriate predicative replacement [Linsky,B] |
| 21703 | Types are 'ramified' when there are further differences between the type of quantifier and its range [Linsky,B] |
| 21714 | The ramified theory subdivides each type, according to the range of the variables [Linsky,B] |
| 21713 | Did logicism fail, when Russell added three nonlogical axioms, to save mathematics? [Linsky,B] |
| 21715 | For those who abandon logicism, standard set theory is a rival option [Linsky,B] |
| 21719 | Extensionalism means what is true of a function is true of coextensive functions [Linsky,B] |
| 21721 | Higher types are needed to distinguished intensional phenomena which are coextensive [Linsky,B] |
| 21723 | The task of logicism was to define by logic the concepts 'number', 'successor' and '0' [Linsky,B] |
| 21727 | Definite descriptions theory eliminates the King of France, but not the Queen of England [Linsky,B] |
| 21729 | Construct properties as sets of objects, or say an object must be in the set to have the property [Linsky,B] |