 In Book \(\Gamma\) of the Metaphysics, Aristotle introduced (what was later to be called) the LNC as “the most certain of all principles” (1005b24)—firmissimum omnium principiorum, as the Medieval theologians said. Since Aristotle, there have been few sustained attempts to defend the law. The LNC has been an (often unstated) assumption, felt to be so fundamental to rationality that some claim it cannot be defended, e.g. David Lewis 1999. As a challenge to the LNC, therefore, dialetheism assails what most philosophers take to be unassailable common sense, calling into question the rules for what can be called into question (cf. Woods 2003, 2005; Dutilh Novaes 2008). 