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Single Idea 16864

[filed under theme 6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / a. Axioms for numbers ]

Full Idea

If the law [of induction] can be proved, it will be included amongst the theorems of mathematics; if it cannot, it will be included amongst the axioms.

Gist of Idea

If principles are provable, they are theorems; if not, they are axioms

Source

Gottlob Frege (Logic in Mathematics [1914], p.203)

Book Ref

Frege,Gottlob: 'Posthumous Writings', ed/tr. Hermes/Long/White etc [Blackwell 1979], p.203


A Reaction

This links Frege with the traditional Euclidean view of axioms. The question, then, is how do we know them, given that we can't prove them.


The 20 ideas with the same theme [general ideas about giving arithmetic a formal basis]:

We know mathematical axioms, such as subtracting equals from equals leaves equals, by a natural light [Leibniz]
Kant suggested that arithmetic has no axioms [Kant, by Shapiro]
Axioms ought to be synthetic a priori propositions [Kant]
The only axioms needed are for equality, addition, and successive numbers [Mill, by Shapiro]
Dedekind gives a base number which isn't a successor, then adds successors and induction [Dedekind, by Hart,WD]
Arithmetical statements can't be axioms, because they are provable [Frege, by Burge]
If principles are provable, they are theorems; if not, they are axioms [Frege]
Numbers have been defined in terms of 'successors' to the concept of 'zero' [Peano, by Blackburn]
Number theory just needs calculation laws and rules for integers [Hilbert]
The definition of order needs a transitive relation, to leap over infinite intermediate terms [Russell]
Axiom of Archimedes: a finite multiple of a lesser magnitude can always exceed a greater [Russell]
It is conceivable that the axioms of arithmetic or propositional logic might be changed [Putnam]
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]
Mathematics is generalisations about singleton functions [Lewis]
The number of Fs is the 'successor' of the Gs if there is a single F that isn't G [Smith,P]
All numbers are related to zero by the ancestral of the successor relation [Smith,P]
Mereological arithmetic needs infinite objects, and function definitions [Reck/Price]
The truth of the axioms doesn't matter for pure mathematics, but it does for applied [Mares]
It is more explanatory if you show how a number is constructed from basic entities and relations [Koslicki]