Why did Joseph Priestley continue to defend the phlogiston theory after Antoine Lavoisier’s work?

Joseph Priestley’s continued defense of the phlogiston theory after Antoine Lavoisier’s work was rooted in both his scientific philosophy and his religious convictions as a Dissenter.1

Priestley viewed the rapid adoption of Lavoisier’s "new system of chemistry" as an imposition of dogma, which he likened to the religious and political pressures exerted by the Anglican establishment. His opposition was driven by a belief that the French chemists were relying on speculative theorizing rather than the patient, humble observation of nature.1

For Priestley, chemistry was intended to support piety and liberty; he argued that the field should avoid abstract systems and instead focus on the empirical study of God’s benevolent creation. In his later publications, such as Doctrine of Phlogiston Established, and That of the Composition of Water Refuted, he sought to highlight what he perceived as the theoretical and methodological flaws in the oxygen theory, maintaining his commitment to an older framework despite the growing scientific consensus favoring Lavoisier’s oxidation model.12