The cat is on the mat' so that he can say which proposition it is. This implies the ability to differentiate between competing propositions and pick out the correct one. We have seen that understanding the sentence is not a requirement for someone to know the proposition expressed by the sentence. Someone could be presented with a sentence in a language unknown to them but understand the translation of that sentence in the, or a, language in which they were fluent and know that sentence to be true. At this point some comments are in order.
Sense is an over-arching component that determines the above scheme.
It is responsible for the scheme going right or wrong. The distinction of sense from reference is required because we need to specify the association between the elements of the object language and the things in the world these element are intended to pick out. This is the advantage of Frege's theory. It seems that Dummett charges the Davidsonian theory with this inadequacy. When Dummett, admittedly briefly, offers an account of the Davidsonian proposal he says that a knowledge of this reconstrued definition of 'true', in addition to a adequate grasp of the concept of truth, would confer an understanding of the language.