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Hale on Caesar. (English) Zbl 0938.01016
This paper is about the problem if the principle: The number of $$Fs$$ is the same as the number of $$Gs$$ just in case the $$Fs$$ can be one-one correlated with the $$Gs$$,
suffices as an explication of the concept of number. This problem was brought up by G. Frege in his Grundlagen der Arithmetik, and Frege explained why - in his opinion - the answer must be negative. Recently, Crispin Wright and Bob Hale expressed their disagreement with Frege. They invoke a so-called Sortal Inclusion Principle in order to defend their positive answer to the above question. The authors now explain why they find the position taken by Wright and Hale unsatisfying.

##### MSC:
 01A55 History of mathematics in the 19th century 00A30 Philosophy of mathematics 03-03 History of mathematical logic and foundations
##### Keywords:
G. Frege; Sortal inclusion principle
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