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Single Idea 9894

[filed under theme 6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / m. One ]

Full Idea

A unit is that according to which each existing thing is said to be one.

Gist of Idea

A unit is that according to which each existing thing is said to be one

Source

Euclid (Elements of Geometry [c.290 BCE], 7 Def 1)

Book Ref

Euclid: 'Euclid's Elements of Geometry (Gk/Eng)', ed/tr. Fitzpatrick,R [Lulu 2007], p.194


A Reaction

See Frege's 'Grundlagen' §29-44 for a sustained critique of this. Frege is good, but there must be something right about the Euclid idea. If I count stone, paper and scissors as three, each must first qualify to be counted as one. Psychology creeps in.


The 12 ideas from Euclid

Proof reveals the interdependence of truths, as well as showing their certainty [Euclid, by Frege]
If you pick an arbitrary triangle, things proved of it are true of all triangles [Euclid, by Lemmon]
Euclid's geometry is synthetic, but Descartes produced an analytic version of it [Euclid, by Resnik]
An assumption that there is a largest prime leads to a contradiction [Euclid, by Brown,JR]
Postulate 2 says a line can be extended continuously [Euclid, by Shapiro]
Euclid relied on obvious properties in diagrams, as well as on his axioms [Potter on Euclid]
Euclid's parallel postulate defines unique non-intersecting parallel lines [Euclid, by Friend]
Euclid needs a principle of continuity, saying some lines must intersect [Shapiro on Euclid]
Euclid says we can 'join' two points, but Hilbert says the straight line 'exists' [Euclid, by Bernays]
Modern geometries only accept various parts of the Euclid propositions [Russell on Euclid]
A unit is that according to which each existing thing is said to be one [Euclid]
Euclid's common notions or axioms are what we must have if we are to learn anything at all [Euclid, by Roochnik]