The papers in this special issue bring together a wide variety of perspectives on the Delphi technique(s) from some of the most important contributors to the thinking and development of the method of the last forty-fifty years. The ubiquity of application
that they hint at suggests that, in many domains, the method has filled a deep need of academics and practitioners for structured ways of assessing and combining human judgement. The more exposure the method gains, the greater its uptake; in many cases,
Delphi seems to be a method that enables researchers to ask and answer questions that, previously, they did not know how to address.