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Single Idea 12211

[filed under theme 6. Mathematics / C. Sources of Mathematics / 1. Mathematical Platonism / b. Against mathematical platonism ]

Full Idea

It is not implausible that before the 'introduction' of complex numbers, it would have been incorrect for mathematicians to claim that there was a solution to the equation 'x^2 = -1' under a completely unrestricted understanding of 'there are'.

Gist of Idea

It is plausible that x^2 = -1 had no solutions before complex numbers were 'introduced'

Source

Kit Fine (The Question of Ontology [2009])

Book Ref

'Metametaphysics', ed/tr. Chalmers/Manley/Wasserman [OUP 2009], p.163


A Reaction

I have adopted this as the crucial test question for anyone's attitude to platonism in mathematics. I take it as obvious that complex numbers were simply invented so that such equations could be dealt with. They weren't 'discovered'!


The 9 ideas from 'The Question of Ontology'

It is plausible that x^2 = -1 had no solutions before complex numbers were 'introduced' [Fine,K]
The indispensability argument shows that nature is non-numerical, not the denial of numbers [Fine,K]
Just as we introduced complex numbers, so we introduced sums and temporal parts [Fine,K]
'Exists' is a predicate, not a quantifier; 'electrons exist' is like 'electrons spin' [Fine,K]
Ontological claims are often universal, and not a matter of existential quantification [Fine,K]
The existence of numbers is not a matter of identities, but of constituents of the world [Fine,K]
Real objects are those which figure in the facts that constitute reality [Fine,K]
Being real and being fundamental are separate; Thales's water might be real and divisible [Fine,K]
For ontology we need, not internal or external views, but a view from outside reality [Fine,K]