Suppose some x comes into existence at t, persists for a while, and then ceases to exist. Question is: can x ‘return’ (yu’ād) to existence, say at t’? Assume that sort of thing can happen. If so, then t would also have to return to existence alongside x, insofar as it is a part of what individuates x as x. But in that case, t and t’ would be identical; and therefore, x’s return to existence would be the same thing as its beginning of existence. But that’s clearly a contradiction. And thus, the initial assumption is necessarily false.
Here are some comments meant to explicate the arguments contained in paragraphs 1-3 of the shaykh’s Al-Shifa’; Ilahiyyat I.7, which is meant to show that the notion of necessity of existence (wajib al-wujud) can’t belong to more than one entity (dhat). I’ll quote the shaykh’s text and then comment accordingly. Read more