The "trust" heuristic: arguments from authority in public health.

The work of public health depends on a relationship of trust between health workers and members of the public. This relationship is one in which the public must trust the advice of health experts, even if that advice is not always readily understood or judged to be agreeable. However, it will be argued in this article that the pact of trust between public health workers and members of the public has been steadily eroded over many years. The reasons for this erosion are examined as are attempts to characterize the concept of trust in empirical studies. The discussion then considers how a so-called informal fallacy, known as the "argument from authority," might contribute to attempts to understand the trust relationship between the public and health experts. Specifically, this argument enables the lay person to bridge gaps in knowledge and arrive at judgements about public health problems by attending to certain logical and epistemic features of expertise. The extent to which lay people are able to discern these features is considered by examining the results of a study of public health reasoning in 879 members of the public.