Columnist Michael Gerson and commentator Amy Holmes are teaming to start a conservative-oriented talk show on PBS... The new show, “In Principle,” will air Friday nights starting April 13. PBS will decide after an eight-week run whether to continue. The hosts plan to interview two guests each show, hoping for an in-depth discussion on issues and their formative political experiences. No guests have been announced yet, but Gershon said he’d like to discuss issues like race, gun control and whether conservatism is the right message for the working class.