The mistake we are liable to make could be expressed thus: We are looking for the use of a sign, but we look for it as though it were an object co-existing with the sign.
A concept, Frege (1892b) argued, is, as a rule, something under which a given object may or may not fall; hence it is a way of classifying objects into two groups (those falling under it and those not falling under it); and so it can be identified with a function mapping objects on the two truth values – truth and falsity.
Restricting ourselves to the two most prominent reducienda of the meaning of an expression, namely the use of the expression and the mental entity ('cognitive content') 'behind' the expression, the following main possibilities seem to emerge as to what a diagram associated with a sentence, or, more generally, with an expression, can amount to: (i) a description of the meaning of the expression (ii) a description of the way the expression is used 6 (iii) a description of a mental entity associated with the expression (iv) a translation of the sentence into another language The first alternative seems to offer the most promising route: what could be a more direct realisation of the task of semantics than displaying expressions alongside with their meanings?8 However, this proposal is rather tricky; for what could count as a description of meaning, which, as we have concluded in the preceding section, is best seen not as a 'real' object, but rather as a value?
The meaning of an expression is, according to it, not a language-independent object casually linked to the expression, rather it is the value of the expression, its position within the system of language or within the language game to be played.
Semiotics, then, is not concerned with the study of a particular kind of object, but with ordinary objects in so far (and only in so far) as they participate in semiosis.'
Frege (1892) recognized that if we identify the meaning of an expression with the real-world object which it is felt the expression normally stands for (the meaning of the expression Morning star with the planet Venus, for example), then we shall not be always able to recover the meaning of a complex expression from the meanings of its parts.
Within the semiotic approach such relations are considered to be mere auxiliaries: saying that two expressions are synonymous is considered to be a mere shortcut for saying that they are linked to the same object.
However, what is synonymy, if it is not the linkage to the same object?
The task of an expression may - in a particular case - be seen as representing an object, as being a name; in such a case its value may possibly be identified with the object.
If it is the process of semiosis that establishes the link between an expression and its meaning, then there is no room for any kind of indeterminacy: there must be a determinate, pre-existing object that becomes meaning through semiosis.