In classical logic, a contradiction consists of a logical incompatibility between two or more propositions. It occurs when the propositions, taken together, yield two conclusions which form the logical inversions of each other. Illustrating a general tendency in applied logic, Aristotle’s law of noncontradiction states that “One can't say of something that it's and that it isn't in the same respect and at the same time.” By extension, outside of classical logic, one can speak… (More on Contradiction)