38°C: Fever, Thermometry, and the Coming into Being of a Global Norm, ca. 1868–1890

The positivist founders of the discipline of history of science would have dismissed the question—of why 37°C and 38°C became a global norm—since they would have thought the answer to be self-evident: Both travelled to distant societies because they were a truth revealed, “hidden nature” brought to light, based on mathematical reasoning and as such “ecumenical” and of universal validity.6 Present-day historians of science would beg to differ, of course. Not only is there reason to doubt that thermometry reveals a universal truth: Studies conducted since the 1990s have found that the normal, oral temperature of adults is lower than the 37°C established in the mid-1800s, either because historic measurements were flawed or because human body temperature has decreased since the Industrial Revolution, when inflammatory levels were higher than today.7 More importantly, ever since scholars began to argue in the 1970s that the validity and the credibility of a proposition are not one and the same—that truth does not shine by its own light, as Steven Shapin put it, that it is not its own sufficient recommendation—the field has made it one of its central tenets to account for how and why something becomes a collectively held knowledge, or norm, “regardless of [its] truth and falsity.”8 One need not go quite so far; indeed, the truth—as well as the accuracy and practical utility—of thermometry’s early propositions were in some measure relevant to their credibility, as the following argues; they were, however, but one, and not a sufficient reason for 38°C becoming a medical fact on a global scale.