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Single Idea 8997

[filed under theme 6. Mathematics / B. Foundations for Mathematics / 3. Axioms for Geometry ]

Full Idea

We can construe geometry by 1) identifying it with algebra, which is then defined on the basis of logic; 2) treating it as hypothetical statements; 3) defining it contextually; or 4) making it true by fiat, without making it part of logic.

Gist of Idea

There are four different possible conventional accounts of geometry

Source

Willard Quine (Truth by Convention [1935], p.99)

Book Ref

Quine,Willard: 'Ways of Paradox and other essays' [Harvard 1976], p.99


A Reaction

[Very compressed] I'm not sure how different 3 is from 2. These are all ways to treat geometry conventionally. You could be more traditional, and say that it is a description of actual space, but the multitude of modern geometries seems against this.


The 10 ideas from 'Truth by Convention'

Logic needs general conventions, but that needs logic to apply them to individual cases [Quine, by Rey]
Claims that logic and mathematics are conventional are either empty, uninteresting, or false [Quine]
Logic isn't conventional, because logic is needed to infer logic from conventions [Quine]
If a convention cannot be communicated until after its adoption, what is its role? [Quine]
Quine quickly dismisses If-thenism [Quine, by Musgrave]
If mathematics follows from definitions, then it is conventional, and part of logic [Quine]
If analytic geometry identifies figures with arithmetical relations, logicism can include geometry [Quine]
Definition by words is determinate but relative; fixing contexts could make it absolute [Quine]
If if time is money then if time is not money then time is money then if if if time is not money... [Quine]
There are four different possible conventional accounts of geometry [Quine]