in ordinary language, signifies any position assumed without proof, or one which is considered as self-evident. In geometry it is applied to whatever is to be assumed or taken for granted; as in Euclid's three postulates, which differ from his axioms in the manner in which they are put. The former is put forward as an assertion, the latter as a request. In philosophy it means any proposition of which the truth is demanded or assumed for the purposes of future reasoning.