Retrieving an insight dating back to antiquity, Bernard Manin argues that the confrontation of opposing views and arguments is beneficial to any political deliberation. But freedom of speech and diversity among deliberators do not suffice to secure that outcome; we must actively facilitate the presentation of contrary opinions during deliberation. Such confrontation is our best means of improving the quality of collective decisions. It also counteracts the pernicious fragmentation of the public sphere. It facilitates the comprehension of choices. And it treats minority voices with respect. This essay proposes practical ways of promoting adversarial deliberation, in particular the organization of debates disconnected from electoral competition.