The role of labor unions in American life was once so vast and profound that it affected virtually everyone. But that was a long time ago. Labor’s influence has declined to such a degree that it’s fair to ask if unions have much relevance at all today. Bob tackles this subject with his guest, Richard Greenwald, a labor historian and co-editor of the book, “Labor Rising.” Professor Greenwald is also the dean of the School of Humanities and Social Sciences at Brooklyn College.