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Single Idea 21557

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

Full Idea

Quine (1941) said that Russell had confused use and mention, and thus thought he had reduced classes to linguistic entities, while in fact he reduced them only to Platonic properties.

Gist of Idea

Russell confused use and mention, and reduced classes to properties, not to language

Source

report of Willard Quine (Whitehead and the Rise of Modern Logic [1941]) by Douglas Lackey - Intros to Russell's 'Essays in Analysis' p.133

Book Ref

Russell,Bertrand: 'Essays in Analysis', ed/tr. Lackey,Douglas [George Braziller 1973], p.133


A Reaction

This is cited as the 'orthodox critical interpretation' of Russell and Whitehead. Confusion of use and mention was a favourite charge of Quine's.


The 23 ideas with the same theme [theory that maths is a hierarchy of set types]:

Frege's logic has a hierarchy of object, property, property-of-property etc. [Frege, by Smith,P]
The ramified theory of types used propositional functions, and covered bound variables [Russell/Whitehead, by George/Velleman]
The Russell/Whitehead type theory was limited, and was not really logic [Friend on Russell/Whitehead]
For 'x is a u' to be meaningful, u must be one range of individuals (or 'type') higher than x [Russell]
In 'x is a u', x and u must be of different types, so 'x is an x' is generally meaningless [Russell, by Magidor]
Type theory cannot identify features across levels (because such predicates break the rules) [Morris,M on Russell]
Classes are defined by propositional functions, and functions are typed, with an axiom of reducibility [Russell, by Lackey]
Type theory seems an extreme reaction, since self-exemplification is often innocuous [Swoyer on Russell]
Russell's improvements blocked mathematics as well as paradoxes, and needed further axioms [Russell, by Musgrave]
Type theory means that features shared by different levels cannot be expressed [Morris,M on Russell]
The 'simple theory of types' distinguishes levels among properties [Ramsey, by Grayling]
Russell confused use and mention, and reduced classes to properties, not to language [Quine, by Lackey]
Simple type theory has 'levels', but ramified type theory has 'orders' [Bostock]
Chihara's system is a variant of type theory, from which he can translate sentences [Chihara, by Shapiro]
We can replace type theory with open sentences and a constructibility quantifier [Chihara, by Shapiro]
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]
Higher types are needed to distinguished intensional phenomena which are coextensive [Linsky,B]
In the unramified theory of types, the types are objects, then sets of objects, sets of sets etc. [George/Velleman]
The theory of types seems to rule out harmless sets as well as paradoxical ones. [George/Velleman]
Type theory has only finitely many items at each level, which is a problem for mathematics [George/Velleman]
Type theory prohibits (oddly) a set containing an individual and a set of individuals [George/Velleman]
Set theory was liberated early from types, and recent truth-theories are exploring type-free [Halbach]