H. P. Grice: For instance, it is quite natural to say to somebody, when we are discussing some concert, My aunt's cousin went to that concert, when we know perfectly well that the person we are talking to is very likely not even to know that we have an aunt, let alone know that our aunt has a cousin. So the supposition must be not that it is common knowledge but rather that it is noncontroversial, in the sense that it is something that we would expect the hearer to take from us (if he does not already know). That is to say, I do not expect, when I tell someone that my aunt's cousin went to a concert, to be questioned whether I have an aunt and, if so, whether my aunt has a cousin. This is the sort of thing that I would expect him to take from me, that is, to take my word for.

For instance, it is quite natural to say to somebody, when we are discussing some concert, My aunt's cousin went to that concert, when we know perfectly well that the person we are talking to is very likely not even to know that we have an aunt, let alone know that our aunt has a cousin. So the supposition must be not that it is common knowledge but rather that it is noncontroversial, in the sense that it is something that we would expect the hearer to take from us (if he does not already know). That is to say, I do not expect, when I tell someone that my aunt's cousin went to a concert, to be questioned whether I have an aunt and, if so, whether my aunt has a cousin. This is the sort of thing that I would expect him to take from me, that is, to take my word for.