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Single Idea 17826

[filed under theme 6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory ]

Full Idea

The standard account of the relationship between numbers and sets is that numbers simply are certain sets. This has the advantage of ontological economy, and allows numbers to be brought within the epistemology of sets.

Gist of Idea

Standardly, numbers are said to be sets, which is neat ontology and epistemology

Source

Penelope Maddy (Sets and Numbers [1981], III)

Book Ref

'Philosophy of Mathematics: anthology', ed/tr. Jacquette,Dale [Blackwell 2002], p.347


A Reaction

Maddy votes for numbers being properties of sets, rather than the sets themselves. See Yourgrau's critique.

Related Idea

Idea 17823 If mathematical objects exist, how can we know them, and which objects are they? [Maddy]


The 57 ideas from Penelope Maddy

New axioms are being sought, to determine the size of the continuum [Maddy]
The Axiom of Extensionality seems to be analytic [Maddy]
Extensional sets are clearer, simpler, unique and expressive [Maddy]
The Iterative Conception says everything appears at a stage, derived from the preceding appearances [Maddy]
Limitation of Size is a vague intuition that over-large sets may generate paradoxes [Maddy]
The Axiom of Infinity states Cantor's breakthrough that launched modern mathematics [Maddy]
Infinite sets are essential for giving an account of the real numbers [Maddy]
The Power Set Axiom is needed for, and supported by, accounts of the continuum [Maddy]
Efforts to prove the Axiom of Choice have failed [Maddy]
Modern views say the Choice set exists, even if it can't be constructed [Maddy]
A large array of theorems depend on the Axiom of Choice [Maddy]
The Axiom of Choice paradoxically allows decomposing a sphere into two identical spheres [Maddy]
Hilbert's geometry and Dedekind's real numbers were role models for axiomatization [Maddy]
The connection of arithmetic to perception has been idealised away in modern infinitary mathematics [Maddy]
Every infinite set of reals is either countable or of the same size as the full set of reals [Maddy]
Critics of if-thenism say that not all starting points, even consistent ones, are worth studying [Maddy]
Set-theory tracks the contours of mathematical depth and fruitfulness [Maddy]
If two mathematical themes coincide, that suggest a single deep truth [Maddy]
The extension of concepts is not important to me [Maddy]
Mathematics rests on the logic of proofs, and on the set theoretic axioms [Maddy]
'Propositional functions' are propositions with a variable as subject or predicate [Maddy]
Infinity has degrees, and large cardinals are the heart of set theory [Maddy]
For any cardinal there is always a larger one (so there is no set of all sets) [Maddy]
Axiom of Reducibility: propositional functions are extensionally predicative [Maddy]
We can get arithmetic directly from HP; Law V was used to get HP from the definition of number [Maddy]
Frege solves the Caesar problem by explicitly defining each number [Maddy]
Cantor and Dedekind brought completed infinities into mathematics [Maddy]
In the ZFC hierarchy it is impossible to form Frege's set of all three-element sets [Maddy]
Theorems about limits could only be proved once the real numbers were understood [Maddy]
Identifying geometric points with real numbers revealed the power of set theory [Maddy]
The line of rationals has gaps, but set theory provided an ordered continuum [Maddy]
Making set theory foundational to mathematics leads to very fruitful axioms [Maddy]
Unified set theory gives a final court of appeal for mathematics [Maddy]
Set theory brings mathematics into one arena, where interrelations become clearer [Maddy]
Completed infinities resulted from giving foundations to calculus [Maddy]
The Axiom of Foundation says every set exists at a level in the set hierarchy [Maddy]
Axiom of Infinity: completed infinite collections can be treated mathematically [Maddy]
'Forcing' can produce new models of ZFC from old models [Maddy]
A Large Cardinal Axiom would assert ever-increasing stages in the hierarchy [Maddy]
An 'inaccessible' cardinal cannot be reached by union sets or power sets [Maddy]
Scientists posit as few entities as possible, but set theorist posit as many as possible [Maddy]
The theoretical indispensability of atoms did not at first convince scientists that they were real [Maddy]
Science idealises the earth's surface, the oceans, continuities, and liquids [Maddy]
Maybe applications of continuum mathematics are all idealisations [Maddy]
Maddy replaces pure sets with just objects and perceived sets of objects [Maddy, by Shapiro]
Intuition doesn't support much mathematics, and we should question its reliability [Maddy, by Shapiro]
We know mind-independent mathematical truths through sets, which rest on experience [Maddy, by Jenkins]
A natural number is a property of sets [Maddy, by Oliver]
Henkin semantics is more plausible for plural logic than for second-order logic [Maddy]
If mathematical objects exist, how can we know them, and which objects are they? [Maddy]
Set theory (unlike the Peano postulates) can explain why multiplication is commutative [Maddy]
The master science is physical objects divided into sets [Maddy]
Standardly, numbers are said to be sets, which is neat ontology and epistemology [Maddy]
Numbers are properties of sets, just as lengths are properties of physical objects [Maddy]
Sets exist where their elements are, but numbers are more like universals [Maddy]
Number words are unusual as adjectives; we don't say 'is five', and numbers always come first [Maddy]
Number theory doesn't 'reduce' to set theory, because sets have number properties [Maddy]