Frege, Contextuality and Compositionality

The name ‘Frege’s principle’ is well known: it is discussed, obeyed or rejected in philosophy, linguistics, logic and computer science (see e.g. [33] and[45]). Surprisingly, two completely different principles which are denoted by that name. In most fields it refers to ‘the principle of compositionality of meaning’: The meaning of a compound expression is a function of the meaning of its parts and of the syntactic rule by which they are combined. But many philosophers understand it as the ‘context principle’ or ‘the principle of contextuality’. That is a principle that Frege mentions in the beginnings of ‘Grundlagen der Arithmetik’: Never ask for the meaning of a word in isolation, but only in the context of a sentence Authors who interpret the principle in the one way, often are not aware of the fact that others do so in the other way. An impressive description of the intellectual landscape in which the two interpretations bloom is given by Pelletier [45]. In this article I will investigate whether the name ‘Frege’s principle’ is justified in view of Frege’s writings. Did he accept both principles at the same time, did he hold the one principle but not the other, or did he at some moment change his opinion?