Two basic expectations of public governance appear to lie in sharp tension. One is that public decision making should involve democratic participation by citizens, through voting or other means. The other is that decision making should be deliberative—for example, informed, cooperative, reflective, and capable of issuing sound policy and law. Classically, governance was understood as either democratic or deliberative, but seldom both at once. Observers from Aristotle to Mill noted this deliberative tension.1 Yet in recent decades it has seemed to grow more acute. Runaway policy complexity—in economics, the environment, international affairs, etc.—coexists uneasily with the global rise of direct lay-citizen input into lawmaking.2 Moreover, timeworn models of representative government, beset by polarization and other problems, often fail to meet the deliberative demands of contemporary lawmaking.

One extraordinary response to the deliberative tension has been a partial reorientation of political theory over two decades or more. In that time, the burgeoning literature of deliberative democracy has solidified a number of central questions and propositions. A particular concern in the field is whether the tension is to some extent illusory, and whether in fact particular governance models can sometimes robustly encourage democratic participation and deliberation at once.3

Some authors in the field's sizeable normative strand of research even stress that only governance able to achieve this goal qualifies as legitimate.4 To be sure, the task of accommodating both deliberation and democracy is profoundly vexed. Yet to many deliberativists, the status quo in governance is more problematic still, and perhaps even untenable. For instance, the deliberative tension is one likely cause of the long crisis of legitimacy afflicting developed democracies since the 1960s, reflected in largely unbroken trends of declining public trust.5 Unable or unwilling to meet both deliberative and democratic demands, a government's perceived legitimacy may weaken—along with its capacity to respond to pressing challenges facing the polity.