Categories: Disambiguation The word validation has several related meanings: In general, validation is the process of checking if something satisfies a certain criterion. ... In mathematics, a proof is a demonstration that, assuming certain axioms, some statement is necessarily true. ... In science and the philosophy of science, falsifiability, contingency, and defeasibility are roughly equivalent terms referring to the property of empirical statements that they must admit of logical counterexamples. ... Forgery is the process of making or adapting objects or documents (see false document), with the intention to deceive. ... In philosophy and logic, the liar paradox encompasses paradoxical statements such as: Analysing the statement I am lying now. ...