Disagreement among experts about public health decision making: is it polarisation and does it matter?

It is common for aspects of the COVID-19 response-and other public health initiatives before it-to be described as polarised. Public health decisions emerge from an interplay of facts, norms and preferred courses of action. What counts as 'evidence' is diverse and contestable, and disagreements over how it should be interpreted are often the product of differing choices between competing values. We propose a definition of polarisation for the context of public health expertise that acknowledges and accounts for epistemic and social values as part of evidence generation and its application to public health practice. The 'polarised' label should be used judiciously because the descriptor risks generating or exacerbating the problem by oversimplifying complex issues and positions and creating groups that seem dichotomous. 'Independence' as a one-size-fits-all answer to expert polarisation is insufficient; this solution is premised on a scientistic account of the role of evidence in decision making and does not make room for the value difference that is at the heart of both polarisation and evidence-based decision making.