At the time the First Amendment was adopted, as today, there were those unscrupulous enough and skillful enough to use the deliberate or reckless falsehood as an effective political tool. . . . That speech is used as a tool for political ends does not automatically bring it under the protective mantle of the Constitution. For the use of the known lie as a tool is at once at odds with the premises of democratic government and with the orderly manner in which economic, social or political change is to be effected.