Any contradiction or paradox.
In the thought of the German philosopher Immanuel Kant (1724–1804): an apparent contradiction between valid conclusions; a paradox.
A logical inconsistency among two or more elements or propositions.
A statement that contradicts itself, i.e., a statement that claims that the same thing is true and that it is false at the same time and in the same senses of the terms.
The act of contradicting.
A proposition that is false for all values of its propositional variables or Boolean atoms.