Do doctors really know what they are talking about when they tell us vaccines are safe? Should we take climate experts at their word when they warn us about the perils of global warming? Oreskes shows how consensus is a crucial indicator of when a scientific matter has been settled, and when the knowledge produced is likely to be trustworthy.

Naomi Oreskes is professor of the history of science and affiliated professor of Earth and planetary sciences at Harvard University. Her books include The Collapse of Western Civilization: A View from the Future and Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming. Oreskes is on Twitter @NaomiOreskes