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Single Idea 17923

[filed under theme 6. Mathematics / A. Nature of Mathematics / 5. The Infinite / a. The Infinite ]

Full Idea

For intuitionists, all but the smallest, most well-behaved infinities are rejected.

Gist of Idea

Intuitionists only accept a few safe infinities

Source

Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 1.1.3)

Book Ref

Colyvan,Mark: 'An Introduction to the Philosophy of Mathematics' [CUP 2012], p.7


A Reaction

The intuitionist idea is to only accept what can be clearly constructed or proved.


The 21 ideas from Mark Colyvan

Reducing real numbers to rationals suggested arithmetic as the foundation of maths [Colyvan]
Intuitionists only accept a few safe infinities [Colyvan]
Rejecting double negation elimination undermines reductio proofs [Colyvan]
Showing a disproof is impossible is not a proof, so don't eliminate double negation [Colyvan]
Excluded middle says P or not-P; bivalence says P is either true or false [Colyvan]
Ordinal numbers represent order relations [Colyvan]
Axioms are 'categorical' if all of their models are isomorphic [Colyvan]
Löwenheim proved his result for a first-order sentence, and Skolem generalised it [Colyvan]
Structuralism say only 'up to isomorphism' matters because that is all there is to it [Colyvan]
If 'in re' structures relies on the world, does the world contain rich enough structures? [Colyvan]
Proof by cases (by 'exhaustion') is said to be unexplanatory [Colyvan]
Reductio proofs do not seem to be very explanatory [Colyvan]
If inductive proofs hold because of the structure of natural numbers, they may explain theorems [Colyvan]
Transfinite induction moves from all cases, up to the limit ordinal [Colyvan]
Mathematical generalisation is by extending a system, or by abstracting away from it [Colyvan]
Mathematics can show why some surprising events have to occur [Colyvan]
Mathematics can reveal structural similarities in diverse systems [Colyvan]
Most mathematical proofs are using set theory, but without saying so [Colyvan]
Infinitesimals were sometimes zero, and sometimes close to zero [Colyvan]
Can a proof that no one understands (of the four-colour theorem) really be a proof? [Colyvan]
Probability supports Bayesianism better as degrees of belief than as ratios of frequencies [Colyvan]