The use of "no evidence" statements in public health

Public health communication makes extensive use of a linguistic formulation that will be called the "no evidence" statement. This is a written or spoken statement of the form "There is no evidence that P" where P stands for a proposition that typically describes a human health risk. Danger lurks in these expressions for the hearer or reader who is not logically perspicacious, as arguments that use them are only warranted under certain conditions. The extent to which members of the public are able to determine what those conditions are will be considered by examining data obtained from 879 subjects. The role of "no evidence" statements as cognitive heuristics in public health reasoning is considered

Coping with uncertainty in public health: the use of heuristics

The observation that experts and lay people use cognitive shortcuts or heuristics to arrive at judgements about complex problems is certainly not new. But what is new is the finding that a group of reasoning strategies, which have been maligned by philosophers and logicians alike, have demonstrable value in helping members of the public come to a judgement about public health problems. These problems, which span food safety crises, immunization scares and risks associated with exposure to environmental toxins, presuppose knowledge and expertise which falls outside of the epistemic and technical competence of most members of the public. Notwithstanding the complexity of these problems, they are not perceived by lay people to be wholly unintelligible or incomprehensible. This short communication reports on the findings of a questionnaire-based investigation into the use of these reasoning strategies by 879 members of the public. The results reveal a rational competence on the part of lay people which has been hitherto unexamined, and which may be usefully exploited in all aspects of public health work

Circles and analogies in public health reasoning

The study of the fallacies has changed almost beyond recognition since Charles Hamblin called for a radical reappraisal of this area of logical inquiry in his 1970 book Fallacies. The “witless examples of his forbears” to which Hamblin referred have largely been replaced by more authentic cases of the fallacies in actual use. It is now not unusual for fallacy and argumentation theorists to draw on actual sources for examples of how the fallacies are used in our everyday reasoning. However, an aspect of this move towards greater authenticity in the study of the fallacies, an aspect which has been almost universally neglected, is the attempt to subject the fallacies to empirical testing of the type which is more commonly associated with psychological experiments on reasoning. This paper addresses this omission in research on the fallacies by examining how subjects use two fallacies – circular argument and analogical argument – during a reasoning task in which subjects are required to consider a number of public health scenarios. Results are discussed in relation to a view of the fallacies as cognitive heuristics that facilitate reasoning in a context of uncertainty

Pragmatic disorders and their social impact

Pragmatic disorders in children and adults have been the focus of clinical investigations for approximately 40 years. In that time, clinicians and researchers have established a diverse range of pragmatic phenomena that are disrupted in these disorders. Pragmatic deficits include problems with the use and understanding of speech acts, the processing of non-literal language, failure to adhere to Gricean maxims in conversation and discourse deficits. These deficits are found in several clinical populations including individuals with autistic spectrum disorders, schizophrenia, traumatic brain injury and right-hemisphere damage. However, what is less often investigated is the social impact of pragmatic disorders on the children and adults who are affected by them. In this paper, I examine what is known about pragmatic disorders in these clinical groups. I then consider the wider social consequences of these disorders, where consequences are broadly construed to include factors that act as indicators of social adjustment

Emerging infectious diseases: coping with uncertainty

The world’s scientific community must be in a state of constant readiness to address the threat posed by newly emerging infectious diseases. Whether the disease in question is SARS in humans or BSE in animals, scientists must be able to put into action various disease containment measures when everything from the causative pathogen to route(s) of transmission is essentially uncertain. A robust epistemic framework, which will inform decision-making, is required under such conditions of uncertainty. I will argue that this framework should have reasoning at its centre and, specifically, that forms of reasoning beyond deduction and induction should be countenanced by scientists who are confronted with emerging infectious diseases. In previous articles, I have presented a case for treating certain so-called traditional informal fallacies as rationally acceptable forms of argument that can facilitate scientific inquiry when little is known about an emerging disease. In this paper, I want to extend that analysis by highlighting the unique features of these arguments that makes them specially adapted to cope with conditions of uncertainty. Of course, such a view of the informal fallacies must at least be consistent with the reasoning practices of scientists, and particularly those scientists (viz. epidemiologists) whose task it is to track and respond to newly emerging infectious diseases. To this end, I draw upon examples of scientific reasoning from the UK’s BSE crisis, a crisis that posed a significant threat to both human and animal health

Reasoning under uncertainty: the role of two informal fallacies in an emerging scientific inquiry

It is now commonplace in fallacy inquiry for many of the traditional informal fallacies to be viewed as reasonable or non-fallacious modes of argument. Central to this evaluative shift has been the attempt to examine traditional fallacies within their wider contexts of use. However, this pragmatic turn in fallacy evaluation is still in its infancy. The true potential of a contextual approach in the evaluation of the fallacies is yet to be explored. I examine how, in the context of scientific inquiry, certain traditional fallacies function by conferring epistemic gains upon inquiry. Specifically, I argue that these fallacies facilitate the progression of inquiry, particularly in the initial stages of inquiry when the epistemic context is one of uncertainty. The conception of these fallacies that emerges is that of heuristics of reasoning in contexts of epistemic uncertainty

Establishing diagnostic criteria: the role of clinical pragmatics

The study of pragmatic disorders is of interest to speech-language pathologists who have a professional responsibility to assess and treat communication impairments. However, these disorders, it will be argued in this paper, have a significance beyond the clinical management of clients with communication impairments. Specifically, pragmatic disorders can now make a contribution to the diagnosis of a range of clinical conditions in which communication is adversely affected. These conditions include attention deficit hyperactivity disorder (ADHD), the autistic spectrum disorders, schizophrenia and the dementias. Pragmatic disorders are already among the criteria used to diagnose some of these conditions (e.g. ADHD), although they are not described in these terms. In other conditions (e.g. the dementias), pragmatic disorders have potential diagnostic value in the absence of reliable biomarkers markers of these conditions and similar initial presenting symptoms. Using clinical data, and the findings of empirical studies, the case is made for the inclusion and/or greater integration of pragmatic disorders in the formal classificatory systems that are used to diagnose a range of disorders. A previously unrecognised role for pragmatic impairments in the nosology and diagnosis of clinical disorders is thereby established

Scaring the public: fear appeal arguments in public health reasoning

The study of threat and fear appeal arguments has given rise to a sizeable literature. Even within a public health context, much is now known about how these arguments work to gain the public's compliance with health recommendations. Notwithstanding this level of interest in, and examination of, these arguments, there is one aspect of these arguments that still remains unexplored. That aspect concerns the heuristic function of these arguments within our thinking about public health problems. Specifically, it is argued that threat and fear appeal arguments serve as valuable shortcuts in our reasoning, particularly when that reasoning is subject to biases that are likely to diminish the effectiveness of public health messages. To this extent, they are rationally warranted argument forms rather than fallacies, as has been their dominant characterization in logic