Shanteau [17] questions the convergence of expert opinion which is based on the widespread use of statistics and economics in assessments and on the widespread search for generalizability in how people think about risks. Shanteau argues then that the bases of convergence are in themselves flawed (see also [18] [19] [20] ). Of course, it is recognised that different risk logics or discourses -i.e. different conceptions of an activity or event as risk -exist, but these have seldom been applied to expert opinion (see [21, 22] ). Silva et al. [23] show, in an experimental setting, that despite differences in scientific background and political beliefs, scientists tend towards a precautionary stance over the setting of safety standards. Yet scientists are not the only type of expert involved in such matters. McMahan et al., [24] point to the differences in how scientists and risk assessors regard electric and magnetic fields. Furthermore, Chalmers et al. [25] show how the opinions of dentists and nursing directors vary over dental care in nursing homes. Chociolko [26] provides an example of expert disagreement often found in sometimes adversarial settings in which experts 'take sides' representing, say, industry or community.