Those of us who walk across bridges in support of reconciliation, and sign Sorry Day books, do so because we feel an obligation to recognise and apologise for the destructive legacy of past practices. Sometimes we can speak directly to those people who were taken away; often we are addressing their descendants. As the prime minister continues to point out, many of us are apologising for something for which we are not individually responsible. So what is the source of this sense of obligation, and how can saying sorry make a difference?