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Full Idea
Given the reference (bedeutung) of an expression and a part of it, obviously the reference of the remaining part is not always determined. So we may not define a symbol or word by defining an expression in which it occurs, whose remaining parts are known
Gist of Idea
We can't define a word by defining an expression containing it, as the remaining parts are a problem
Source
Gottlob Frege (Grundgesetze der Arithmetik 2 (Basic Laws) [1903], §66)
Book Ref
Frege,Gottlob: 'The Frege Reader', ed/tr. Beaney,Michael [Blackwell 1997], p.268
A Reaction
Dummett cites this as Frege's rejection of contextual definitions, which he had employed in the Grundlagen. I take it not so much that they are wrong, as that Frege decided to set the bar a bit higher.
| 13886 | Later Frege held that definitions must fix a function's value for every possible argument [Frege, by Wright,C] |
| 9889 | Real numbers are ratios of quantities [Frege, by Dummett] |
| 10553 | A number is a class of classes of the same cardinality [Frege, by Dummett] |
| 10020 | Frege's biggest error is in not accounting for the senses of number terms [Hodes on Frege] |
| 9886 | Cardinals say how many, and reals give measurements compared to a unit quantity [Frege] |
| 9890 | The modern account of real numbers detaches a ratio from its geometrical origins [Frege] |
| 9891 | The first demand of logic is of a sharp boundary [Frege] |
| 10019 | Only what is logically complex can be defined; what is simple must be pointed to [Frege] |
| 9845 | We can't define a word by defining an expression containing it, as the remaining parts are a problem [Frege] |
| 9887 | Formalism misunderstands applications, metatheory, and infinity [Frege, by Dummett] |
| 8751 | Only applicability raises arithmetic from a game to a science [Frege] |
| 11846 | If we abstract the difference between two houses, they don't become the same house [Frege] |