As the law stands at present, a general election must be held at intervals not exceeding five years. On these occasions the ordinary British citizen suddenly finds himself, often to his own surprise, sovereign for a day. By his vote he can seal the fate of a political party for the next few years. At such times party propaganda reaches its pinnacle of intensity, and the voter is approached by letter, the canvasser, the press, and the broadcaster to support this or that policy. Not infrequently tariff questions form a prominent feature of an election campaign, and the voter has put before him all sorts of economic or other reasons why import taxes should or should not be imposed. In the great majority of cases he has no knowledge or training to form a considered judgment on such difficult problems, and there is little doubt that he is swayed one way or the other by the skill with which arguments are presented, rather than by their validity. The sledgehammer propaganda of the poster has more value at an election time than any scientific exposition.