Ideally, public knowledge should encapsulate the achievements of millennia of inquiry, making them available to individuals and groups for the promotion of their various ends. I explore the ways in which the actual situation fails to live up to this ideal. Our investigations are not always directed towards the questions of most concern to most people, the results on which experts agree are not always based on reasons the broader public is prepared to endorse, and the dissemination of information is so distorted as to make supposedly free discussion and debate an unproductive shouting match. The consequences for democracy are severe, since a healthy system of public knowledge, able to discharge its function, is an essential component of a flourishing democratic society. (Contains 13 notes.)