This chapter outlines a theory of a central function of social governance and an important function of democracy—assessing consequences of social policy—that underlies the need to create social knowledge. It argues that democracies work more effectively when basic social knowledge is more widely shared, because at election time citizens must rely on information to assess whether the proposed policies of their leaders are broadly sound. Modern information technology can facilitate acquiring social knowledge by reducing information costs. Reducing information costs has four large advantages for social decision making. Among these is that reducing information costs can create more knowledge about public policy and reduce the cost of accessing knowledge. Another advantage is that reducing information costs better enables citizens to organize around encompassing interests that many of them have in common, such as good education and economic growth.