  Aristotle explains that, given its peculiar status as the firmest first principle, PNC is not susceptible to demonstration. A demonstration is a deductive argument, the conclusion of which is deduced from firmer, prior premises. It follows that if PNC could be deduced from another premise, then that premise would have to be a firmer and prior principle, with the result that PNC could not have been the firmest first principle.  Aristotle also says that if PNC could be demonstrated, then everything would be subject to demonstration, which would lead to an infinite regress. Therefore demonstration is ruled out, and one must be wary of reconstructions of Aristotle’s discussion in terms of ordinary deductive arguments. Anyone asking for a deductive argument for PNC, as Aristotle points out, is missing the point, or, rather, is asking for something that is impossible without using PNC. You cannot engage in argument unless you rely on PNC. Anyone who claims to reject PNC “for the sake of argument” is similarly misguided.