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Single Idea 9911

[filed under theme 6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / a. Structuralism ]

Full Idea

Questions of the identification of the referents of number words should be dismissed as misguided in just the way that a question about the referents of the parts of a ruler would be seen as misguided.

Gist of Idea

Number words no more have referents than do the parts of a ruler

Source

Paul Benacerraf (What Numbers Could Not Be [1965], IIIC)

Book Ref

'Philosophy of Mathematics: readings (2nd)', ed/tr. Benacerraf/Putnam [CUP 1983], p.292


A Reaction

What a very nice simple point. It would be very strange to insist that every single part of the continuum of a ruler should be regarded as an 'object'.


The 24 ideas from 'What Numbers Could Not Be'

Benacerraf says numbers are defined by their natural ordering [Benacerraf, by Fine,K]
To understand finite cardinals, it is necessary and sufficient to understand progressions [Benacerraf, by Wright,C]
Disputes about mathematical objects seem irrelevant, and mathematicians cannot resolve them [Benacerraf, by Friend]
No particular pair of sets can tell us what 'two' is, just by one-to-one correlation [Benacerraf, by Lowe]
A set has k members if it one-one corresponds with the numbers less than or equal to k [Benacerraf]
We can count intransitively (reciting numbers) without understanding transitive counting of items [Benacerraf]
Someone can recite numbers but not know how to count things; but not vice versa [Benacerraf]
The application of a system of numbers is counting and measurement [Benacerraf]
To explain numbers you must also explain cardinality, the counting of things [Benacerraf]
For Zermelo 3 belongs to 17, but for Von Neumann it does not [Benacerraf]
The successor of x is either x and all its members, or just the unit set of x [Benacerraf]
Numbers can't be sets if there is no agreement on which sets they are [Benacerraf]
Number words are not predicates, as they function very differently from adjectives [Benacerraf]
The set-theory paradoxes mean that 17 can't be the class of all classes with 17 members [Benacerraf]
Identity statements make sense only if there are possible individuating conditions [Benacerraf]
If ordinal numbers are 'reducible to' some set-theory, then which is which? [Benacerraf]
If any recursive sequence will explain ordinals, then it seems to be the structure which matters [Benacerraf]
The job is done by the whole system of numbers, so numbers are not objects [Benacerraf]
The number 3 defines the role of being third in a progression [Benacerraf]
Number words no more have referents than do the parts of a ruler [Benacerraf]
Number-as-objects works wholesale, but fails utterly object by object [Benacerraf]
There are no such things as numbers [Benacerraf]
Mathematical objects only have properties relating them to other 'elements' of the same structure [Benacerraf]
How can numbers be objects if order is their only property? [Benacerraf, by Putnam]