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Single Idea 17611

[filed under theme 6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / g. Real numbers ]

Full Idea

It then only remained to discover its true origin in the elements of arithmetic and thus at the same time to secure a real definition of the essence of continuity.

Gist of Idea

We want the essence of continuity, by showing its origin in arithmetic

Source

Richard Dedekind (Continuity and Irrational Numbers [1872], Intro)

Book Ref

Dedekind,Richard: 'Essays on the Theory of Numbers' [Dover 1963], p.2


A Reaction

[He seeks the origin of the theorem that differential calculus deals with continuous magnitude, and he wants an arithmetical rather than geometrical demonstration; the result is his famous 'cut'].


The 28 ideas from Richard Dedekind

We want the essence of continuity, by showing its origin in arithmetic [Dedekind]
Arithmetic is just the consequence of counting, which is the successor operation [Dedekind]
A cut between rational numbers creates and defines an irrational number [Dedekind]
If x changes by less and less, it must approach a limit [Dedekind]
I say the irrational is not the cut itself, but a new creation which corresponds to the cut [Dedekind]
Dedekindian abstraction talks of 'positions', where Cantorian abstraction talks of similar objects [Dedekind, by Fine,K]
Dedekind has a conception of abstraction which is not psychologistic [Dedekind, by Tait]
Dedekind said numbers were abstracted from systems of objects, leaving only their position [Dedekind, by Dummett]
Categoricity implies that Dedekind has characterised the numbers, because it has one domain [Rumfitt on Dedekind]
Dedekind gives a base number which isn't a successor, then adds successors and induction [Dedekind, by Hart,WD]
Zero is a member, and all successors; numbers are the intersection of sets satisfying this [Dedekind, by Bostock]
Induction is proved in Dedekind, an axiom in Peano; the latter seems simpler and clearer [Dedekind, by Russell]
Dedekind's axiom that his Cut must be filled has the advantages of theft over honest toil [Dedekind, by Russell]
Dedekind says each cut matches a real; logicists say the cuts are the reals [Dedekind, by Bostock]
Dedekind proved definition by recursion, and thus proved the basic laws of arithmetic [Dedekind, by Potter]
Dedekind's ordinals are just members of any progression whatever [Dedekind, by Russell]
Dedekind defined the integers, rationals and reals in terms of just the natural numbers [Dedekind, by George/Velleman]
Order, not quantity, is central to defining numbers [Dedekind, by Monk]
Ordinals can define cardinals, as the smallest ordinal that maps the set [Dedekind, by Heck]
Numbers are free creations of the human mind, to understand differences [Dedekind]
In counting we see the human ability to relate, correspond and represent [Dedekind]
Dedekind originated the structuralist conception of mathematics [Dedekind, by MacBride]
An infinite set maps into its own proper subset [Dedekind, by Reck/Price]
Dedekind originally thought more in terms of mereology than of sets [Dedekind, by Potter]
A thing is completely determined by all that can be thought concerning it [Dedekind]
We have the idea of self, and an idea of that idea, and so on, so infinite ideas are available [Dedekind, by Potter]
A system S is said to be infinite when it is similar to a proper part of itself [Dedekind]
We derive the natural numbers, by neglecting everything of a system except distinctness and order [Dedekind]