LEARNING OBJECTIVES: Readers of this chapter will
- appreciate the range of mundane contexts in which we are exposed to medical information and health messages.
- understand the different responses that people have to health messages, ranging from indifference and denial to a high level of critical engagement with the content of messages.
- appreciate the need for robust critical thinking skills in medicine and health in order to expose logical errors and conflicts of interest in the health messages we see and hear, participate in sound decision-making about one’s own health, and reduce or eliminate medical errors that put patients at risk of death or serious injury.
- have knowledge of what an informal fallacy is and understand that labels such as ‘valid’ and ‘fallacious’ are not inherent properties of arguments but apply only to arguments in certain contexts of use.
- understand the logical tradition that surrounds the fallacies, from Aristotle’s challenge to the deceptive or false refutations traded by sophists to present-day pragmatic and cognitive analyses of the fallacies.
1.1 Introduction
Imagine for a moment all the different ways in which you are exposed to medical stories and health messages in a typical day. Over breakfast, you turn on the television and hear that a study has found that coffee consumption reduces the risk of coronary heart disease . As you drive to work, a report about dementia comes over the car radio. You listen closely enough to understand that a lack of exercise significantly increases the risk of developing dementia. You get to your office and learn that one of your colleagues was admitted to hospital overnight with a suspected stroke . You are surprised to hear this news as you know your colleague is only 50 years old and takes good care of his health. So you go online to learn more about stroke and its causes. You have a busy schedule at work and decide to dash out of the office to buy a sandwich. You normally buy a chicken sandwich but you saw a television programme at home the previous evening about salmonella in poultry. So you decide to ‘play safe’ and opt for a tuna sandwich instead. You finally get out of work at 6 o’clock. As you drive home, you stop at traffic lights and have a couple of minutes to read an advertisement on a billboard at the side of the road. It states the number of units of alcohol that can be safely consumed in a week. You know that you are exceeding these limits, but you quickly put this thought out of your mind as the lights change and you drive off. Your evening at home passes quickly, and it is not long before you are going to bed. You take one of your prescribed sleeping pills and happen to notice a warning on the box that you should not consume alcohol . You know it has been four hours since you had two glasses of wine over dinner and so you do not consider yourself to be at any harm from the drug.
What I have described above is a series of unremarkable events. Most readers will be able to identify with one or more of the circumstances in this scenario. It illustrates the extent to which medical and health messages pervade our daily lives. On some occasions, these messages leave little permanent trace in our minds. We may read the public health advertisement about safe levels of alcohol consumption and then almost instantly forget it. On other occasions, these messages may have increased salience for us. For example, we may listen to a report about dementia with heightened interest if a family member or friend is suffering from the condition, or if we recently participated in a fundraising event in support of a dementia charity. Whatever response we take to these medical stories and health messages, they involve complex cognitive processes such as reasoning , perception, and language decoding. We may reason, for example, that a message has limited relevance to our personal health because we do not engage in a particular behaviour (e.g. alcohol consumption). Alternatively, we may reason that a message is relevant to our health but that we have little or no individual control over a source of risk (e.g. air pollution), and so any modification of behaviour is unlikely to result in health gains. At other times, a health message may encourage us to avoid eating certain foods, or to take more cardiovascular exercise, or to get a flu vaccination or other form of immunisation. The reasoning processes that guide each of these responses are a focus of intellectual curiosity for a wide range of scholars. This book seeks to understand these processes by conducting an in-depth examination of their application to medicine and health.
This book will argue that a special type of reasoning is involved in the mundane scenario outlined above. This reasoning allows us to come to judgement on an issue by means of shortcuts or quick rules of thumb that may be used to bypass knowledge, facts, and evidence about a problem. To this extent, it is a powerful cognitive resource that can serve us well when we are confronted by complex health issues that lie beyond our current state of knowledge. But this resource can also be abused and misused, leading to flawed, defective reasoning . The reasoning in question is best represented by a group of arguments known as the informal fallacies. These arguments have occupied a less than auspicious position in the long history of logic . Denigrated for their lack of deductive credentials, these arguments languished in a state of relative neglect until a group of pioneering logicians forced a reconsideration of their logical merits. The work of these so-called informal logicians prompted a sustained effort to characterize non-fallacious variants of most of the informal fallacies. These logicians also pursued a more systematic analysis of the many ways in which these arguments may be used illegitimately during reasoning and argumentation . The result of this resurgence of scholarly interest in the fallacies has been new analytical frameworks and theoretical possibilities. The various logical developments that have moved us beyond a wholesale rejection of the fallacies towards a more enlightened approach to the logical merits of these arguments will be examined in Sect. 1.4. But first, we must address a more fundamental question. That is the question of why it is important to have a set of rational evaluative skills that can be applied to medicine and health. It is to this question that we now turn.
1.2 Why Think Critically about Medicine and Health?
There are several reasons why it is important to have a set of critical thinking skills that can be applied to medicine and health. As the scenario in Sect. 1.1 illustrates, we cannot evade the relentless exposure to medical and health messages that is part of our daily lives. We would be naïve to think that all, or even most, of these messages are conveying claims that represent some ideal of scientific truth and objectivity. For example, people may not be so ready to accept the claim that coffee consumption reduces the risk of coronary heart disease if they were to discover that a large coffee manufacturer funded the study that produced this finding, or if they were to learn that the study examined a small sample of young, healthy participants over a relatively short period of time. By the same token, a public health advertising campaign about safe levels of alcohol intake loses some of its credibility if a trade association for the alcohol industry has contributed funding to the campaign. It may be legitimately asked if the definition of ‘safe’ might not have involved a smaller number of weekly units of alcohol if funding for the campaign had not been obtained from the alcohol industry. Each of these conflicts of interest and aberrations of scientific methodology (e.g. the use of a small, unrepresentative sample) passes undetected and unchallenged by people who lack critical thinking skills that can be applied to medicine and health. It is not an exaggeration to claim that medicine and health suffer when citizens, who are deprived of robust critical thinking skills, are unable to hold the individuals, agencies, and organizations responsible for health information and messages to proper rational scrutiny. This point will be emphasized many times in the chapters to follow.
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