Metacognition and Contested Science: The Case of Water Fluoridation.

Community water fluoridation (CWF) has become one of the most contested public health interventions despite a robust evidence base supporting its effectiveness, safety, and equity. Drawing on a recent comprehensive review, this perspective argues that persistent controversies revolve not only around the effectiveness, safety, and implementation of CWF but also around a "fourth controversy": how people evaluate and hold confidence in what they think they know. We discuss CWF as a case of contested science in which polarization and misinformation undermine belief updating. Using insights from metacognition research, we suggest that improving public reasoning requires communication and policy approaches that foster epistemic humility, iterative learning, and evidence-informed revision rather than reliance on evidence accumulation alone.