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6. Mathematics / C. Sources of Mathematics / 5. Numbers as Adjectival

[numbers as properties, rather than objects]

14 ideas
Just as unity is not a property of a single thing, so numbers are not properties of many things [William of Ockham]
     Full Idea: Number is nothing but the actual numbered things themselves. Hence just as unity is not an accident added to the thing which is one, so number is not an accident of the things which are numbered.
     From: William of Ockham (Summa totius logicae [1323], I.c.xliv)
     A reaction: [William does not necessarily agree with this view] It strikes me as a key point here that any account of the numbers had better work for 'one', though 'zero' might be treated differently. Some people seem to think unity is a property of things.
Numbers are a very general property of objects [Mill, by Brown,JR]
     Full Idea: Mill held that numbers are a kind of very general property that objects possess.
     From: report of John Stuart Mill (System of Logic [1843], Ch.4) by James Robert Brown - Philosophy of Mathematics
     A reaction: Intuitively this sounds hopeless, because if you place one apple next to another you introduce 'two', but which apple has changed its property? Both? It seems to be a Cambridge change. It isn't a change that would bother the apples. Kitcher pursues this.
It appears that numbers are adjectives, but they don't apply to a single object [Frege, by George/Velleman]
     Full Idea: Numbers as adjectives appear to attribute a property - but to what? Superficially it seems to be to the objects themselves, as it makes sense to say that a plague is 'deadly', but not that it is 'ten'.
     From: report of Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.2
     A reaction: Surely they could be adjectival if they were properties of groups? Groups can be 'numerous', or 'more than a hundred', or 'too many for this taxi'.
Numerical adjectives are of the same second-level type as the existential quantifier [Frege, by George/Velleman]
     Full Idea: A numerical adjective forms part of a predicate of second-level, needing supplementation from the first level (F). So the second-level predicate is of the same type as the existential quantifier, and can be called a 'numerical quantifier'.
     From: report of Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.2
     A reaction: This seems like a highly plausible account of how numbers work in language, but it leaves you wondering what the ontological status of a quantifier is. I presume platonic heaven is not full of elite entities called quantifiers, marshalling the others.
'Jupiter has many moons' won't read as 'The number of Jupiter's moons equals the number many' [Rumfitt on Frege]
     Full Idea: 'Jupiter has four moons' is semantically and syntactically on all fours with 'Jupiter has many moons'. But it would be brave to construe the latter proposition as a transformation of 'The number of Jupiter's moons is identical with the number many'.
     From: comment on Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884]) by Ian Rumfitt - Concepts and Counting p.49
     A reaction: I take this to be an important insight. Number words are continuous with (are in the same category as) words for general numerical quantity, such as 'just a few' or 'many' or 'rather a lot'. Numbers are part of normal language.
The number 'one' can't be a property, if any object can be viewed as one or not one [Frege]
     Full Idea: How can it make sense to ascribe the property 'one' to any object whatever, when every object, according as to how we look at it, can be either one or not one?
     From: Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884], §30)
     A reaction: This remark seems to point to numbers being highly subjective, but the interest of Frege is that he then makes out a case for numbers being totally objective, despite being entirely non-physical in nature. How do they do that?
For science, we can translate adjectival numbers into noun form [Frege]
     Full Idea: We want a concept of number usable for science; we should not, therefore, be deterred by everyday language using numbers in attributive constructions. The proposition 'Jupiter has four moons' can be converted to 'the number of Jupiter's moons is four'.
     From: Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884], §57)
     A reaction: Critics are quick to point out that this could work the other way (noun-to-adjective), so Frege hasn't got an argument here, only an escape route. How about the verb version ('the moons of Jupiter four'), or the adverb ('J's moons behave fourly')?
Maybe numbers are adjectives, since 'ten men' grammatically resembles 'white men' [Russell]
     Full Idea: 'Ten men' is grammatically the same form as 'white men', so that 10 might be thought to be an adjective qualifying 'men'.
     From: Bertrand Russell (Introduction to Mathematical Philosophy [1919], XVIII)
     A reaction: The immediate problem, as Frege spotted, is that such expressions can be rephrased to remove the adjective (by saying 'the number of men is ten').
Number words are not predicates, as they function very differently from adjectives [Benacerraf]
     Full Idea: The unpredicative nature of number words can be seen by noting how different they are from, say, ordinary adjectives, which do function as predicates.
     From: Paul Benacerraf (What Numbers Could Not Be [1965], II)
     A reaction: He points out that 'x is seventeen' is a rare construction in English, unlike 'x is happy/green/interesting', and that numbers outrank all other adjectives (having to appear first in any string of them).
Ordinals are mainly used adjectively, as in 'the first', 'the second'... [Bostock]
     Full Idea: The basic use of the ordinal numbers is their use as ordinal adjectives, in phrases such as 'the first', 'the second' and so on.
     From: David Bostock (Philosophy of Mathematics [2009], 9.5.iii)
     A reaction: That is because ordinals seem to attach to particulars, whereas cardinals seem to attach to groups. Then you say 'three is greater than four', it is not clear which type you are talking about.
Treating numbers adjectivally is treating them as quantifiers [Wright,C]
     Full Idea: Treating numbers adjectivally is, in effect, treating the numbers as quantifiers. Frege observes that we can always parse out any apparently adjectival use of a number word in terms of substantival use.
     From: Crispin Wright (Frege's Concept of Numbers as Objects [1983], 1.iii)
     A reaction: The immediate response to this is that any substantival use can equally be expressed adjectivally. If you say 'the number of moons of Jupiter is four', I can reply 'oh, you mean Jupiter has four moons'.
Number words are unusual as adjectives; we don't say 'is five', and numbers always come first [Maddy]
     Full Idea: Number words are not like normal adjectives. For example, number words don't occur in 'is (are)...' contexts except artificially, and they must appear before all other adjectives, and so on.
     From: Penelope Maddy (Sets and Numbers [1981], IV)
     A reaction: [She is citing Benacerraf's arguments]
Empiricists base numbers on objects, Platonists base them on properties [Brown,JR]
     Full Idea: Perhaps, instead of objects, numbers are associated with properties of objects. Basing them on objects is strongly empiricist and uses first-order logic, whereas the latter view is somewhat Platonistic, and uses second-order logic.
     From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 4)
     A reaction: I don't seem to have a view on this. You can count tomatoes, or you can count red objects, or even 'instances of red'. Numbers refer to whatever can be individuated. No individuation, no arithmetic. (It's also Hume v Armstrong on laws on nature).
We might eliminate adjectival numbers by analysing them into blocks of quantifiers [Hofweber]
     Full Idea: Determiner uses of number words may disappear on analysis. This is inspired by Russell's elimination of the word 'the'. The number becomes blocks of first-order quantifiers at the level of semantic representation.
     From: Thomas Hofweber (Number Determiners, Numbers, Arithmetic [2005], §2)
     A reaction: [compressed] The proposal comes from platonists, who argue that numbers cannot be analysed away if they are objects. Hofweber says the analogy with Russell is wrong, as 'the' can't occur in different syntactic positions, the way number words can.