Moore argued that since any such identification gives rise to an open question , it can never be correct. This constitutes a significant reason for concluding that fact and value remain irreducibly distinct. Also see OCP , IEP , and BGHT . Necessary truth is a feature of any statement that it would be contradictory to deny. Stop signs are hexagonal.
Pentagons are round.
Necessity may also be defined de dicto in terms of the formal logical property of tautology . Also see articles on necessary and contingent statements , logical necessity , metaphysical necessity , and necessary and contingent existence in OCP , and Jeffrey C. King . In logic , one proposition is a necessary condition of another when the second cannot be true while the first is false, and one proposition is a sufficient condition for another when the first cannot be true while the second is false. Also see articles on necessary and sufficient conditions , epistemic necessity , and nomic necessity in OCP , Norman Swartz , BGHT , and CE . Therefore, if my daughter is not sixteen, then I am not over thirty.