  Is the status of Aristotle's “first principle” as obvious as he believed? Adherents of the dialetheist view that there are true contradictories (Priest 1987, 1998, 2002; see also the entries  on  dialetheism and  paraconsistent logic) would  answer firmly in the   negative.[6]  In the Western tradition, the countenancing of true contradictions is typically—although not exclusively—motivated on the basis of such classic logical paradoxes as “This sentence is not true” and its analogues; such a statement is evidently true if and only if it is not true. The Liar, or really the family of Liar’s paradoxes (see Liar Paradox), and Russell’s paradox, its set-theoretic analogue (a set that is not a member of itself both is and is not a member of itself—see the entry on   Russell’s Paradox), would no longer constitute immediate threats to logical coherence in the absence of LNC (see papers in Priest et al. for extended discussion). If we are indeed prepared to jettison LNC, we can regard “This sentence is not true” (or “This statement is false”) as simultaneously true and not true without deriving the resultant absurdity taken by Aristotle and his heirs to result from such a contradiction. As Smiley (1993: 19) has remarked, “Dialetheism stands to the classical idea of negation like special relativity to Newtonian mechanics: they agree in the familiar areas but diverge at the margins (notably the paradoxes).”