Much as today, Victorian-era vaccine hesitancy was tied up with distrust of the medical profession and of the power of the modern state. In that period of imperial expansion, it became increasingly important for nations to regulate the health of their populations against epidemics of smallpox, cholera, and other preventable diseases that had the power to roil economies and topple governments. Authorities thus defended mass immunization as a rational scientific program, undertaken for the common good.
Today, whether we realize it or not, we are all implicated in this biopolitical calculus. While most of us are happy to submit to vaccination in our own and other peoples’ interests, a recalcitrant minority see it as an affront to their liberty and freedom of choice. That conflict has been more or less a historical continuum. What is surprising, and demands more explanation, is the persistence of a fear of harm caused by vaccines in the face of overwhelming scientific evidence that vaccination is a boon to health and, for the most part, safe.
Voltaire would have been fascinated by this phenomenon. His letters were in part an attempt to contrast the empiricist psychology of John Locke with the a priori speculations of his countryman René Descartes. Voltaire apprehended that, in its purest, abstract form, reason could be a cul-de-sac that leads one to doubt everything. Instead, he advocated tempering rationalism with observable facts about the world, an empirical approach that was exemplified by Isaac Newton and other leading English scientists associated with the Enlightenment.
What Voltaire could not have foreseen about the situation we face today is that conspiracy theorists would seek to undermine trust in the scientific establishment by turning its observations against it. A prominent feature of contemporary anti-vax websites is that they are not afraid to engage with the science of vaccinology; indeed, many anti-vaxxers have spent more time studying the literature on vaccines than those who tend to take the findings on trust. The difference is that whereas mainstream scientists accept that theories based on empirical observations may change if a better theory comes along, conspiracy theories are by definition unfalsifiable. They are doubt masquerading as truth, rationalism divorced from empiricism.