||It seems obvious that the connection between, on one hand, the sounds, shapes, movements and the like that underwrite language use and, on the other hand, core linguistic properties, like grammatical properties and meanings, is fairly arbitrary. The same sounds, shapes, movements, etc., that are used in English to say that the cat is on the mat could easily have been used to say that the ship is sinking. And other sounds, shapes, movements, etc., could easily have been used to say that the cat is on the mat. The general question that accounts of linguistic convention aim to answer is, how are the connections here instituted? Sometimes 'conventional' is used to indicate the type of connection in question here, in which case it is assumed that the relevant connections are conventional, and the difficulty is to explain in detail the nature of the relevant conventions. Other times, specific accounts are given of what conventions are, and the difficulty is to demonstrate, or explain, whether, and if so how, those accounts apply to the institution of connections in the sphere of language. Taking the latter route, some philosophers have provided detailed accounts of convention on which participation in a convention seems to require mutual knowledge that others are so participating. Other philosophers have argued that such accounts are too demanding, and that less is required to participate in, for example, the use of a language.