Like death, causation is something of a riddle. The death certificate of Queen Elizabeth II has "old age" given as the cause of death - but given that old age is simply an outcome of being alive for a certain period of time, what does it mean to pathologise it in this way, and to list it as a fatal condition? Far from being an exact science, death certification is rife with interpretation and contentious decision-making - and this reflects not only death's enigmatic qualities, but the mysterious nature of causation itself.