Abstract

A number of prominent defenders of the phlogiston theory identified phlogiston with hydrogen in the late eighteenth century, and I argue that this identification was fairly well-entrenched by the early nineteenth century. In light of this identification, I examine the ways in which retaining phlogiston could have retarded scientific progress, and also the ways in which it could have benefited science. I argue that it was rational for chemists to eliminate phlogiston, but that it also would have been rational for them to retain it. I situate my arguments for these claims in relation to Hasok Chang's recent work on the Chemical Revolution. And I conclude that there is a sense in which scientific rationality concerns what is permissible, as opposed to what is required, so that retention and elimination may, at least sometimes, both be rationally permissible options.