This is a comprehensive and systematic exploration of the place of science in democratic societies. In this successor to his pioneering "Science, Truth, and Democracy", renowned philosopher Philip Kitcher explores the challenges of integrating science, the most successful knowledge-generating system of all time, with the problems of democracy. Kitcher considers a variety of examples of pressing concern, ranging from climate change to religiously inspired constraints on biomedical research to the neglect of diseases that kill millions of children annually, analyzing the sources of trouble. He shows the fallacies of thinking that democracy always requires public debate of issues most people cannot comprehend, and argues that properly constituted expertise is essential to genuine democracy.