Negation is a sine qua non of every human language but is absent from otherwise complex systems of animal communication. In many ways, it is negation that makes us human, imbuing us with the capacity to deny, to contradict, to misrepresent, to lie, and to convey irony. The apparent simplicity of logical negation as a one-place operator that toggles truth and falsity belies the intricate complexity of the expression of negation in natural language. Not only do we find negative adverbs, verbs, copulas, quantifiers, and affixes, but the interaction of negation with other operators (including...