I sent the following question to Ask a linguist:
Chomsky made much of the independence or autonomy of syntax with respect to semantics, such as the fact that there are grammatically well-formed sentences that don’t seem to mean anything very much e.g. ‘colourless green ideas sleep furiously’ or Russell’s ‘quadruplicity drinks procrastination’. But is there a way of defining a sentence that doesn’t make use of semantic notions? With semantic notions, there is no problem saying what a sentence is… it is the smallest thing capable of being a move in a language game (Dummett), the expression of a judgement (subsumption of an object under a concept), or the smallest thing capable of being either true or false (Frege). But if these resources are ruled out, what is a sentence from the autonomous perspective of (the study of) syntax?
I’m a bit disappointed with the response which was:
Thank you very much for your query. Unfortunately, we cannot post it as written. In order to keep the volume down, we do not post queries that have answers available in widely available print sources. It appears to us that the answer to your query could be found by looking at several sources, and some recommendations have been provided below. As such we can’t post it. Please do not reply to this email.
All the best,
A standard linguistic definition of a sentence:
The following URL links to several chapters from a book, which may prove helpful:
In other words… go and do your own research. This is disappointing because they do answer questions on technical terms in linguists of the kind you’d expect to find in a linguistics textbook (for instance, this question on the difference between aspect and tense), just not mine. And in any case, I have looked in a couple textbooks for answers and couldn’t find anything that addresses the question. The wikipedia page they refer me to, for instance and to save you the trouble of clicking there, doesn’t give a non-semantic definition of a sentence at all, but a semantic one.
In linguistics, a sentence is an expression in natural language—a grammatical and lexical unit consisting of one or more words, representing distinct and differentiated concepts, and combined to form a meaningful statement, question, request, command, etc. (my emphasis)
I’ll keep looking, but I don’t think the “autonomous” study of syntax can provide a definition of a sentence without invoking semantic notions.