 (This formula is sometimes called “Lambert’s Law,” though the earliest published mention of it was apparently in Hintikka (1959), p. 83.  In the context of Hintikka’s system, however, it had various unwelcome consquences (see Lambert 1962; van Fraassen 1991, pp. 8–10).)  Adding (LL) to the free logic defined by (A1)–(A6) and (A7-) gives the minimal free definite description theory MFD. MFD is the core of virtually all free description theories, which therefore differ only in the additional principles they endorse.