sentences:  Greenberg was an analyst for the conservative Heritage Foundation, a writer for the libertarian Cato Institute, and a teacher at the high school and college level in the fields of philosophy, political science, and computer programming.He published over 100 articles on government and public policy in newspapers, magazines, and academic journals, including "The New York Times", "National Review", "The Monist", and the "Ohio State Law Journal".He has also been president of the Advance Arkansas Institute, senior counsel for the Center for Class Action Fairness, and chair of Arkansas's Alcoholic Beverage Commission.