The “Trust” Heuristic: Arguments from Authority in Public Health

Abstract

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.

ACKNOWLEDGMENT

The author acknowledges with gratitude the comments of two anonymous reviewers of this article. Their comments have been most helpful in revising the article.

Notes

¹ It should be clarified from the outset that the expression “the public” is not intended to suggest a homogeneous group of people. In fact, as applied to public health communication, the notion of “the public” can refer to a quite different demographic with each occasion of use. For example, if the purpose of public health communication is to warn of possible health risks associated with the use of the oral contraceptive pill, “the public” in this case consists of women of child-bearing age who are using, or plan to use, this form of contraception.

2. ²These concerns were raised by Andrew Wakefield and colleagues in an article that appeared in The Lancet (Wakefield et al., 1998). These investigators examined a consecutive series of 12 children with chronic enterocolitis and pervasive developmental disorder. The onset of behavioral symptoms in 8 of the 12 children was associated, by the parents, with MMR vaccination. The ensuing public anxiety about the safety of the MMR vaccine caused a sharp reduction in the number of parents who consented to vaccination of their children.

3. ³Occasionally, studies have reported high levels of trust in public health agencies. Deurenberg-Yap et al. (2005) reported high levels of public trust in the response of Singaporean health authorities to an outbreak of SARS from March 1 to May 11, 2003. More than 80% of a sample of 853 adults agreed that preventive and control measures instituted in response to the outbreak were appropriate. Additionally, more than 93% of subjects indicated that they were satisfied or very satisfied with the government’s response to SARS. High confidence and trust in the actions of the government were in stark contrast to the low knowledge of these subjects about SARS and the control measures undertaken in response to it.

4. ⁴This scandal involved several journalists in the British press media illegally accessing the mobile phone accounts of celebrities, politicians and a murder victim. A YouGov survey of 1,108 adults in the United Kingdom and 1,095 adults in the United States for the first report of the Public Broadcasting Service (PBS) UK Trust revealed that 58% of UK adults said the phone-hacking scandal had reduced their level of trust in the newspaper industry, while 51% said it had reduced their trust in the UK media as a whole.

5. ⁵Of course, there are exceptions. Hilton and Hunt (2011) found that UK newsprint reporting of the swine flu outbreak was largely measured.

6. ⁶NHS Immunisation Statistics for England in 2011–2012 show that MMR vaccination coverage was 91.2%. Although this is still lower than the World Health Organization target of at least 95%, it is comparable to the level of 90.8% in 1997–1998. In the wake of the MMR safety scare, MMR coverage dropped to a low of 79.9% in 2003–2004.

7. ⁷The enduring loss of trust that is the legacy of the BSE crisis is consistent with Slovic’s concept of “trust asymmetry.” In describing this notion, Slovic (1993, p. 677) states that “trust is fragile. It is typically created rather slowly, but it can be destroyed in an instant by a single mishap or mistake.” At the heart of Slovic’s asymmetry principle is the idea that people pay more attention to and are more influenced by negative rather than positive information. This was confirmed in a study by Poortinga and Pidgeon (2004). For participants who were undecided about the risks of genetically modified (GM) food, negative information was found to be more informative than positive information. A number of factors have been found to moderate the effect of message valence (i.e., positive versus negative information) on trust including prior attitudes (White, Pahl, Buehner, & Haye, 2003) and the nature of a hazard in a particular case (White & Eiser, 2005).

8. ⁸Although the focus here is on the pharmaceutical industry, similar comments could be made about other industries including tobacco and alcohol companies, producers of fast foods and GM food, and the nuclear industry. In a study of trust in GM food, Lang and Hallman (2005) found that industry was included in a group of merchants which were least trusted by the public. Other members of this group were farmers, grocers, and grocery stores.

9. ⁹It should be emphasized from the outset that not all empirical studies attribute a significant role to trust in risk perception. In a study of the relationship between trust and risk perception within and across four European countries, Viklund (2000) concluded that although trust was an element in explanatory models of risk perception, it was not as powerful a factor as had been argued in the literature. Sjöberg (2001) argued that trust is of surprisingly minor importance in risk perception because people believe that there are limits on how much science and experts know. This “unknown-effects” factor, it was found, was a more important explanatory factor than trust for the public in risk perception.

10. ¹⁰The work of two fallacy theorists—Douglas Walton and John Woods—has been particularly influential in this regard. In a large number of books and journal articles, these theorists have described nonfallacious forms of petitio principii (begging the question), argumentum ad ignorantiam (the argument from ignorance), and argumentum ad baculum (the argument from the stick or appeal to force), among others (Walton, 1985, 1992; Woods, 1995, 2004). Of course, in emphasizing that there exist nonfallacious variants of the informal fallacies, this is not the same as saying that there are no such things as fallacious arguments. For discussion of novel fallacious arguments in the context of the BSE problem, the reader is referred to Cummings (2005).

11. ¹¹The reduced processing associated with simple heuristics is often associated with increased error. But as Todd and Gigerenzer (2000, p. 727) argue, this is a mistaken assumption with heuristics performing at least as well as more complex forms of reasoning in many contexts: “We show how simple building blocks that control information search, stop search, and make decisions can be put together to form classes of heuristics, including: ignorance-based and one-reason decision making for choice, elimination models for categorization, and satisficing heuristics for sequential search. These simple heuristics perform comparably to more complex algorithms, particularly when generalizing to new data.”

12. ¹²The reader is referred to Walton (2010) for further discussion of the argument from expert opinion as a heuristic. Walton proposes a parascheme for this argument, in which the heuristic is seen to bypass a number of critical questions that normally attend the use of expertise in argumentation.