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Single Idea 10200

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

Full Idea

We must distinguish between 'realism in ontology' - that mathematical objects exist - and 'realism in truth-value', which is suggested by the model-theoretic framework - that each well-formed meaningful sentence is non-vacuously either true or false.

Gist of Idea

We distinguish realism 'in ontology' (for objects), and 'in truth-value' (for being either true or false)

Source

Stewart Shapiro (Philosophy of Mathematics [1997], Intro)

Book Ref

Shapiro,Stewart: 'Philosophy of Mathematics:structure and ontology' [OUP 1997], p.4


A Reaction

My inclination is fairly strongly towards realism of the second kind, but not of the first. A view about the notion of a 'truth-maker' might therefore be required. What do the truths refer to? Answer: not objects, but abstractions from objects.


The 34 ideas with the same theme [reasons for believing maths entities exists]:

One is, so numbers exist, so endless numbers exist, and each one must partake of being [Plato]
We aim for elevated discussion of pure numbers, not attaching them to physical objects [Plato]
In pure numbers, all ones are equal, with no internal parts [Plato]
Geometry is not an activity, but the study of unchanging knowledge [Plato]
We master arithmetic by knowing all the numbers in our soul [Plato]
It is a simple truth that the objects of mathematics have being, of some sort [Aristotle]
Numbers seem to be objects because they exactly fit the inference patterns for identities [Frege]
Frege's platonism proposes that objects are what singular terms refer to [Frege, by Wright,C]
How can numbers be external (one pair of boots is two boots), or subjective (and so relative)? [Frege, by Weiner]
Identities refer to objects, so numbers must be objects [Frege, by Weiner]
Numbers are not physical, and not ideas - they are objective and non-sensible [Frege]
Numbers are objects, because they can take the definite article, and can't be plurals [Frege]
Our concepts recognise existing relations, they don't change them [Frege]
Numbers are not real like the sea, but (crucially) they are still objective [Frege]
Restricted Platonism is just an ideal projection of a domain of thought [Bernays]
Mathematical objects are as essential as physical objects are for perception [Gödel]
Mathematics isn't surprising, given that we experience many objects as abstract [Boolos]
Platonists like axioms and decisions, Aristotelians like definitions, possibilities and logic [Badiou]
Number platonism says that natural number is a sortal concept [Wright,C]
It is claimed that numbers are objects which essentially represent cardinality quantifiers [Hodes]
Numerical terms can't really stand for quantifiers, because that would make them first-level [Hodes]
The Indispensability Argument is the only serious ground for the existence of mathematical entities [Field,H]
We distinguish realism 'in ontology' (for objects), and 'in truth-value' (for being either true or false) [Shapiro]
If mathematical objects are accepted, then a number of standard principles will follow [Shapiro]
Platonists claim we can state the essence of a number without reference to the others [Shapiro]
Platonism must accept that the Peano Axioms could all be false [Shapiro]
Sets are instances of numbers (rather than 'collections'); numbers explain sets, not vice versa [Lowe]
If 2 is a particular, then adding particulars to themselves does nothing, and 2+2=2 [Lowe]
The irrationality of root-2 was achieved by intellect, not experience [Brown,JR]
If there are infinite numbers and finite concrete objects, this implies that numbers are abstract objects [Lowe]
Platonism claims that some true assertions have singular terms denoting abstractions, so abstractions exist [Williamson]
Why is arithmetic hard to learn, but then becomes easy? [Hofweber]
If 'there are red roses' implies 'there are roses', then 'there are prime numbers' implies 'there are numbers' [Schaffer,J]
We can only mentally construct potential infinities, but maths needs actual infinities [Hossack]