“Yeah, but is it art?” R. Crumb’s comic-strip alter ego asked on the poster for this eponymous retrospective at the Museum Ludwig in Cologne. For many audiences, the question might have seemed beside the point. After all, comics have historically been an integral part of cultural heritage in countries like France and Belgium (consider Moebius’s Blueberry or Hergé’s Tintin). Even within the world of fine art, they have seeped in from the margins at least as far back as Joan Miró and Kurt Schwitters, and since Pop art this entertaining medium has widely been considered a worthy source by artists.