Contributor(s): Lord Alderdice, Dr Deirdre MacManus | How much do we know about the psychology of those engaged in the violence of insurgency and counterinsurgency? What are the predispositions and motivations for violence, and what are the psychological consequences of their experiences? From 1987 to 1998 John Alderdice was the leader of Northern Ireland’s cross-community Alliance Party. He has previously served as the consultant–in-charge of the Centre for Psychotherapy, Belfast. Deirdre MacManus is a forensic psychiatrist and clinical lecturer at the Institute of Psychiatry, King’s College London.