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Single Idea 12369

[filed under theme 6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / a. Units ]

Full Idea

Arithmeticians posit that a unit is what is quantitatively indivisible.

Gist of Idea

A unit is what is quantitatively indivisible

Source

Aristotle (Posterior Analytics [c.327 BCE], 72a22)

Book Ref

Aristotle: 'Posterior Analytics (2nd ed)', ed/tr. Barnes,Jonathan [OUP 1993], p.4


A Reaction

Presumably indeterminate stuff like water is non-quantitatively divisible (e.g. Moses divides the Red Sea), as are general abstracta (curved shapes from rectilinear ones). Does 'quantitative' presupposes units, making the idea circular?


The 21 ideas with the same theme [a series of isolated 'ones' on which counting is built]:

Two can't be a self-contained unit, because it would need to be one to do that [Democritus, by Aristotle]
The unit is stipulated to be indivisible [Aristotle]
If only rectilinear figures existed, then unity would be the triangle [Aristotle]
Units came about when the unequals were equalised [Aristotle]
A unit is what is quantitatively indivisible [Aristotle]
Unit is the starting point of number [Aristotle]
Unity is something shared by many things, so in that respect they are equals [Descartes]
I can only see the proportion of two to three if there is a common measure - their unity [Descartes]
Only whole numbers are multitudes of units [Leibniz]
There is no multiplicity without true units [Leibniz]
Number cannot be defined as addition of ones, since that needs the number; it is a single act of abstraction [Fine,K on Leibniz]
Numbers must be assumed to have identical units, as horses are equalised in 'horse-power' [Mill]
You can abstract concepts from the moon, but the number one is not among them [Frege]
Units can be equal without being identical [Tait on Frege]
Frege says only concepts which isolate and avoid arbitrary division can give units [Frege, by Koslicki]
We need 'unities' for reckoning, but that does not mean they exist [Nietzsche]
Multiplicity in general is just one and one and one, etc. [Husserl]
Classes have cardinalities, so their members must all be treated as units [Armstrong]
A number is a multitude composed of units [Dummett]
A one-operation is the segregation of a single object [Kitcher]
Objects do not naturally form countable units [Koslicki]