  It appears that every Argument of the Appendix is logically valid. Like the Arguments of D1 and D2, the Arguments of the Appendix rest on a number of independent premises, including premises of D1 and D2. Again, most of the premises are, at least from Plato’s point of view, either definitionally true or self-evident. (Gill (1996, 86) objects to one of the premises of AppA5. For a rejoinder, see Rickless (2007, 195, n. 2).) There is one major exception to this claim, however. All of the Arguments of the Appendix other than AppA1 depend for their soundness on the soundness of AppA1. But AppA1 depends for its soundness on the soundness of D1A17, which itself depends for its soundness on the truth of Purity-F. So if Purity-F were false, then all the Arguments of the Appendix would be unsound.