Since the retraction of Andrew Wakefield’s 1998 Lancet article that purported a link between MMR vaccine and autism, the subject has faded from being of scientific medical interest. However, public health and social psychology researchers now study it under the rubric of “social judgment theory” to learn how people persuade themselves about an idea (in this case, an idea that is widely known to be wrong). Donald Trump–a walking-talking catalogue of counterfactual ideas–is providing a bonanza of empirical data for this field. Unfortunately, as President he will have the power to turn such ideas into policy. Today, for example, he named a celebrity vaccine skeptic, Robert F. Kennedy Jr., to chair a new commission on vaccine safety and scientific integrity, which implies that there is national concern about vaccines, their medical safety, and the integrity of related science. Of course, there is not. But the sordid political history of certain other famous counterfactual ideas, such as 19th century “scientific racism” and Nazi eugenics, should serve as a warning about the vulnerability of public attitudes to treacherous systems of identity, lifestyle and ideology.
