 The treatise in De Rijk 1966 presents more of a theory. Much of it is obscure to modern scholars, but it seems to appeal to a distinction between a mental act of asserting and a vocal act of uttering a proposition. “Saying” requires both acts; it is “an assertion with utterance”. In the case of the liar who says “What I am saying is false”, the mental act of asserting is present, and for that matter so is the physical act of uttering the words. But somehow (this is the obscure part) there is no “saying”.