Propaganda art can be jarring and crude or beautiful and persuasive. It is a visual tool used by both repressive and democratic nations to convey a message or hammer home a point. A new book offers a collection of propaganda posters from the last century created by governments, rebel groups, nongovernmental organizations and the UN. The World’s co-host Carolyn Beeler speaks with Bradley Davies, the author of “Propagandopolis: A Century of Propaganda from Around the World.”