Abstract

Logicians generally employ coherence and consistency as synonyms naming the absence of contradictions in a group of SENTENCES, propositions, or beliefs, where a contradiction is the conjunction of a proposition and its negation. In metaphysical terms, logical incoherence or contradiction is the impossible instantiation of a property and some other, incompatible property, as in "the circle was square." Epistemically, a contradiction is an irrational belief in both a proposition and its denial.