Presented at the University of Liverpool 7 December 1994 With my presentation there will have been an even dozen Duncan lecturers. It is ex traordinary how the work and character of William Henry Duncan has caused the selection of such a diverse array of themes. Each of the Duncan lectures, however, found in Dr Duncan's work a strand of common cause with their own interests. And I am no exception. Duncan knew from his experience with the authorities, be they governmental or pro fessional, that for public health to advance it must build a public constituency of informed citizens. The horrendous poverty of Liverpool, its crowded housing and lack of sanitation were, of course, obvious to the middle class but the powerful link of such conditions with high levels of morbidity and mortality needed Dr Duncan's documentation to build the basis for public understanding of the public health prevention option. This may have been the first time that a purposeful effort was made to enlist public support for a specific public health action. Since Duncan's day, of course, there has been a steady increase in the encouragement of public in moving the public health agenda forward. Progress toward full public has not, however, been constant or without professional/governmental resistance. Sharon Arnstein, an American cit izen health advocate, developed nearly 25 years ago the so called of participation that described eight levels of participation. These started with informing, consultation, and plac ation and moved to three degrees of what Arnstein referred to as part nership, delegated power, and citizen control.1 Clearly Dr Duncan climbed the first several steps on the ladder and was probably inclined to seek public-professional as well. But nearly a century had passed before serious strategic consideration was given to involving the public as partners in health planning, del egating specific power of self determination in health care, or placing citizens in full control of the health enterprise. We are presently a long way from the latter and are still tentative about partnership and lay self determination in health. We in the health and related professions remain quite caught up in the exclusivity of our qual ifications in health matters and view with suspicion the ability of ordinary citizens to provide criticism or even to comprehend the complexities of health actions, be they at the political or personal level. We are, at the same time, absolutely convinced of the scientific merit and wisdom of our professional expertise. Ordinary citizens have beliefs we have know ledge. This, despite mounting evidence of public competence in health decision-making2 con current with mounting evidence of the fallibility of the medical and public health professions.3 Of course, these two realities are not usually juxtaposed, but professional critiques of the lay role in health have an undercurrent of defensiveness. The view is that the proponents of the lay role, especially in personal care, are reacting critically to limitations of professional care.4 Perhaps. But what this points out is the discomfort health professionals feel as they see the erosion of their power as health and health care become increasingly social ideas where many voices and many resources want to have their contributions acknowledged. The popularisation of health does take its toll on traditional roles, traditional constructions of reality, and the egos invested in them. Is nothing sacred anymore, some ask? Does demo cratisation know no bounds? Will the time come when plebiscites will replace scientific inquiry to determine truth? Will citizen control, ending professional dominance,5 as we have grown to know and cherish it, destroy health gains already achieved? Or are we entering a new era of health development where lay and professional collaboration, with full pro fessional and public oversight will bring us closer to the World Health Organization's ideal istic goal of health for all? What is going on here and where might it take us. In my time with you this evening, I want to respond to these questions as they redefine health as common property, in its achievement, maintenance, and restoration. I cannot profess an unbiased view of consumerism and health, because I could not get away with it for very long anyway. Too many of my British col leagues in the College of Health and the Patients' Association have shared panels or podia with me as we challenged what in earlier days we called the establishment. What saves you (us) from my bias now is that I no longer have to rely on impressions, anecdotes, and rhetoric.