Near the end of Jenny Erpenbeck’s novel Kairos, winner of the International Booker Prize this week, a character embraces strange, new pleasures in her unified German homeland – travel and shoplifting – while asking bigger questions. “Wasn’t it agreed that a unified Germany would get a new constitution?” wonders Katharina as she strolls out of a DIY store with a stolen lawnmower. “Instead, the Basic Law of West Germany has extended its jurisdiction over the East. Was that fair?” It is one of the many questions lingering as Germany marks the 75th anniversary of the Basic Law – das Grundgesetz...