ARGUMENT

argument, a word meaning "proof," "evidence," corresponding in english to the latin word _argumentum_, from which it is derived; the originating latin verb _arguere_, to make clear, from which comes the english "argue," is from a root meaning bright, appearing in greek [greek: argaes], white. from its primary sense are derived such applications of the word as a chain of reasoning, a fact or reason given to support a proposition, a discussion of the evidence or reasons for or against some theory or proposition and the like. more particularly "argument" means a synopsis of the contents of a book, the outline of a novel, play, &c. in logic it is used for the middle term in a syllogism, and for many species of fallacies, such as the _argumentum ad hominem, ad baculum_, &c. (see fallacy). in mathematics the term has received special meanings; in mathematical tables the "argument" is the quantity upon which the other quantities in the table are made to depend; in the theory of complex variables, e.g. such as a + ib where i = [root](-1), the "argument" (or "amplitude") is the angle [theta] given by tan [theta] = b/a. in astronomy, the term is used in connexion with the ptolemaic theory to denote the angular distance on the epicycle of a planet from the true apogee of the epicycle; and the "equation to the argument" is the angle subtended at the earth by the distance of a planet from the centre of the epicycle.