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Faced with the uncertainties of a rapidly evolving pandemic caused by a novel coronavirus, public health agencies employed rational strategies to guide people on protecting themselves against the virus. Some members of the public, however, are susceptible to fallacies which compromised their compliance with important health measures.

Prof. Louise Cummings was in the UK collecting data for her research when the COVID-19 pandemic began. Being an established scholar in the Department of English and Communication of The Hong Kong Polytechnic University, whose research areas include public health communication, she began to observe and record how public health agencies around the world, and individuals from personal acquaintances, responded to the emerging pandemic during the critical first six months.

“I was struck by some of the responses and behaviours that I observed,” Prof. Cummings recounted. “For example, a friend whom I know very well is not inclined to reckless behaviour, nevertheless broke multiple Government lockdown restrictions to travel by train from his hometown to his elderly parents’ home to spend the weekend with them. How can we explain this behaviour?”

Prof. Cummings recognised several types of logical errors and lapses of reasoning which led some people to violate public health measures:
  • Applying qualifications to general statements to which they do not belong. Her friend mentioned above viewed a “hard” generalisation — a government directive expressing people should not undertake non-essential travel during lockdown — as a “soft” generalisation to which he incorrectly considered himself to be a legitimate exception.
  • Failure of relevance. This is the argument from an irrelevant premise. For example, trying to convince someone who was concerned about COVID transmission through close social contacts that, a gathering of friends could be safely held in one’s private home, with no hugging, instead of meeting in a public space.
  • Fallacy of composition. Using a property of a part (such as one’s clothing) to infer the property of a whole (such as one’s body). An observed case was a man who regularly visited his elderly father during the lockdown. He claimed that he presented no health risk to his father because he changed his clothes before entering the house. When in fact, COVID transmits more efficiently from the droplets people emit than via infected clothing.
  • Fallacy of equivocation. The illicit shift in the meaning of words in the premises of an argument. Such was the case when a person argued that because the UK Government allowed people from different households to meet outdoors, he could meet his neighbour in his outdoors garden shed. In the first premise, the word ‘outdoors’ means an unenclosed space in the open air. However, in the second premise, the word ‘outdoors’ means outside the house. The meaning of ‘outdoors’ had shifted from what the Government had intended to an altogether different meaning.

While people grappled with new public health measures designed to control the spread of the virus, their compliance at times compromised by various lapses of reasoning and logical errors, public health agencies around the world employed rationally warranted strategies to formulate advice and guidance:

  • Analogical reasoning. When relatively little was known about this novel coronavirus, much of the initial guidance was based on analogical reasoning and used two other beta coronaviruses (SARS and MERS) as analogues. This was a rationally warranted strategy when decisions must be made, and actions taken without complete data. It was preferable to inaction that could cost lives and erode trust in public health agencies.
  • Arguments from ignorance under a closed-world assumption and exhaustive search criterion. The closed-world assumption requires a knowledge base to contain all the information in a particular domain. The exhaustive search criterion requires full examination of the knowledge base to discover all relevant information. When both conditions are met, then it is possible to conclude that a proposition is true (or false) based on the premise that there is no evidence that it is false (or true). For example, the World Health Organization issued a statement that current serological tests could not establish COVID immunity in an individual based on ignorance reasoning from a closed, exhaustively searched knowledge base of serological tests.

The instances of good and bad reasoning observed by Prof. Cummings illustrated how they could facilitate and compromise compliance with public health measures, respectively. While public health recommendations often assume a rational citizenry that can form logical judgements about health behaviours, this assumption is not always warranted. The COVID-19 pandemic presents a valuable opportunity for scholars of reasoning to help address the public education gap in reasoning and critical thinking. This effort could significantly improve the quality of public health action and decision-making.

More importantly, scholars of reasoning should play an integral role in public health decision-making in real time. They should sit alongside scientists in expert advisory groups. Decisions should be rationally scrutinised as they are taken and not later, when any negative consequences cannot be reversed. If this could be the legacy of COVID-19, subsequent generations might be more adept at responding to the global pandemics that will inevitably afflict them.

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