Rhetoric refers to speaking or writing that is designed to have a persuasive or impressive effect but is lacking in meaningful content. The bias may be for or against certain types of medical intervention or health practices, and can often be identified when arguments are based on opinions or beliefs rather than verifiable facts, or when there is a lack of evidence-based content. Rhetoric may be particularly relevant in online sources of healthcare information, new and emerging technologies and policies not underpinned by high-quality evidence. Rhetoric can often be found in press releases and newspaper articles as a means to entice the reader.
The idea that childhood vaccinations caused autism was widely publicised in 1998. The interpretation of these publications at the time is an example of rhetoric as it provides an unsupported link between autism and vaccination (referred to as the environment).
Since then, the original paper suggesting this link has been shown to be fraudulent and has been retracted, but the idea that there is a link still has an influence.
The use of false claims or reasoning to build an argument, often with an emotional component, can be called biases of rhetoric. The impact is difficult to measure, but clearly, can lead to healthcare decisions not based on evidence.
Awareness remains the most critical aspect in preventing the impact of artful persuasion. Education aimed at developing critical thinking skills, including the public understanding of bias in research, can help people understand the effects of biases of rhetoric. Additionally, we recommend asking for the evidence when it is relevant to decision-making.
To understand why some people are susceptible to claims for health interventions that are ineffective or possibly harmful, we should look at the rhetoric used to persuade them in the first place.