Taylor, Talbot J. (1998) “Do you understand? Criteria of understanding in Verbal Interaction” in Integrational Linguistics: A First Reader (eds.) Roy Harris & George Wolf: 198-208. Oxford: Elsevier Science Ltd.

“To make the words serviceable to the end of communication, it is necessary that they excite, in the Hearer, exactly the same Idea, they stand for in the mind of the Speaker. Without this, Men fill one another’s Heads with noise and sound; but convey not thereby their Thoughts, and lay not before one another their Ideas, which is the end of Discourse and Language.” (Locke 1690, Book III, Ch. 9, Section 6). – 198

We can never know, Locke argues, if the ideas we signify by certain words are the same as  our hearers signify by the very same words. Consequently, we can never be certain that our hearers receive the thoughts we intend by our utterances to convey. That is, the ‘imperfection of words’ consists in the fact that, because the understanding of words is a private, mental event, they do not provide speakers with a means of knowing whether their words are being correctly understood. – 199

From Saussure’s conventionalist point of view, we may be certain that all speakers of the same language link the same ‘signifies’ with the same ‘signifiants’ because that connection is arbitrarily imposed on them by the conventions of their language. Saussure’s reply to Locke’s worries about the intersubjectivity of the connection between words and ideas was to argue, in effect, that speakers and hearers do not possess any ideas other than those given to them by the signs of their language. – 199-200