The title of this periodical is Policy Dialogue. It could just as easily have been Policy Debate but that would have been inconsistent with the purpose and spirit of this publication. Debate is, generally, a zero-sum game. The purpose of debate is to win the argument on its merit – the evidence produced and the logic – and the style of presentation including the points you can score off your opponent, humorously or otherwise. It is stylized combat with little quarter given to your opponent or your opponent’s argument and assumptions. At its best, debate can produce new arguments and new ways of seeing existing problems but, at its worst, debate encourages evidence to be exaggerated and the truth twisted. At its most boring, debate simply raises old arguments in the same old ways. For all of these reasons, policy debate often generates more heat than light. You don’t have to look far to see examples of this, including the current debate over climate change, the subject of four of the essays in this issue of Policy Dialogue.