   A number of “problems” (shubuhāt; the Arabic refers to all forms of obscurities, including what we call paradoxes and sophistries) are attributed to Ibn Kammuna. These have challenged Iranian philosophers in particular from the sixteenth century onwards (Pourjavady &amp; Schmidtke 2006, 37–51). Some but not all can be traced to known writings of Ibn Kammuna. One of these is the famous liar paradox, which Ibn Kammuna discusses in The New Wisdom; some later figures mistakenly thought that Ibn Kammuna had invented it. Another, much discussed item is “the problem of unity” (shubhat al-tawḥīd). Especially since Ibn Sina, the deity was widely identified with wājib al-wujūd, “that whose existence is necessary”; but, as a philosophical category, is “necessary existence” necessarily unique?  Muslim and Jewish thinkers would certainly want it to be so, but proving this point was no simple matter. At one place Ibn Kammuna argues from the interconnectedness of all reality, which implies that a single “necessary existence” must stand at the top of the causal chain.  He may have picked this up from Maimonides who noted in his Guide of the Perplexed (Part I, Ch. 72) that the unity of reality is an important indication for the unity of God. Elsewhere, however, he chose a more torturous route. Were there more than one “necessary existence”, then, rather than being a unique essential characteristic, “necessary existence” would perforce be demoted to the rank of an accident shared by two or more beings. It was this proposal that was debated and criticized by later thinkers.