The question posed in the title of this course contains a double meaning: First, how do scientists deal with epistemic crises that threaten their credibility? And second, how do scientists react in political, epidemiological, or other seemingly external crises that strain their methods and institutions? This course will begin to answer these questions by unpacking the tools that experts use to assert their authority and produce a binding perception of reality. Then, we will consider the way that social movements—including “citizen scientists,” HIV/AIDS activists, and “biohackers”—contest, mistrust, or reaffirm experts’ authority. Finally, we will study how these disputes are shaped by regulatory bureaucracies and the legal system.