Arkansas Rep. Tom Cotton, who announced this week that he will challenge Democratic Sen. Mark Pryor, attacked alcohol vendors, called for mandatory financial disclosures of campaign donations, favored banning cigarettes, and attacked libertarianism while he was a Harvard student. In a twice-weekly column for the Harvard Crimson, Cotton — who has been called a “Republican’s dream” by National Review and an “extraordinary figure” by the Weekly Standard — criticized politicians for not doing enough to oppose tobacco and wrote a laudatory 1996 piece praising Bill and Hillary Clinton. In 1997, Cotton wrote a scolding op-ed on alcohol and underage drinking...