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Single Idea 18164

[filed under theme 6. Mathematics / B. Foundations for Mathematics / 5. Definitions of Number / e. Caesar problem ]

Full Idea

To solve the Julius Caesar problem, Frege requires explicit definitions of the numbers, and he proposes his well-known solution: the number of Fs = the extension of the concept 'equinumerous with F' (based on one-one correspondence).

Gist of Idea

Frege solves the Caesar problem by explicitly defining each number

Source

Penelope Maddy (Naturalism in Mathematics [1997], I.1)

Book Ref

Maddy,Penelope: 'Naturalism in Mathematics' [OUP 2000], p.5


A Reaction

Why do there have to be Fs before there can be the corresponding number? If there were no F for 523, would that mean that '523' didn't exist (even if 522 and 524 did exist)?


The 13 ideas with the same theme [explain why Julius Caesar can't be a number]:

Property extensions outstrip objects, so shortage of objects caused the Caesar problem [Cantor, by Shapiro]
'Julius Caesar' isn't a number because numbers inherit properties of 0 and successor [Frege, by George/Velleman]
From within logic, how can we tell whether an arbitrary object like Julius Caesar is a number? [Frege, by Friend]
Frege said 2 is the extension of all pairs (so Julius Caesar isn't 2, because he's not an extension) [Frege, by Shapiro]
Fregean numbers are numbers, and not 'Caesar', because they correlate 1-1 [Frege, by Wright,C]
One-one correlations imply normal arithmetic, but don't explain our concept of a number [Frege, by Bostock]
The words 'There are exactly Julius Caesar moons of Mars' are gibberish [Rumfitt on Frege]
Our definition will not tell us whether or not Julius Caesar is a number [Frege]
Frege makes numbers sets to solve the Caesar problem, but maybe Caesar is a set! [Bostock]
If numbers are extensions, Frege must first solve the Caesar problem for extensions [Wright,C]
The Julius Caesar problem asks for a criterion for the concept of a 'number' [Hale/Wright]
Frege solves the Caesar problem by explicitly defining each number [Maddy]
Some suggest that the Julius Caesar problem involves category mistakes [Magidor]