“Authoritarian” political systems concentrate power in a lone authority and lack countervailing institutions to meaningfully challenge that authority. All authoritarian political theories and systems derive from what we might call authoritarian theories of knowledge, which designate an authority as the ultimate source of truth. Extended to politics, they designate an authority as the ultimate source of political wisdom: the sovereign who alone possesses the knowledge required to rule. Although different authority-based political theories assert different authorities to be the rightful ruler (e.g., The King or perhaps The People), such theories all assume that the task of politics is to designate an ultimate authority to rule over society. This authoritarian assumption, the core attribute of all such theories, is more fundamental than comparatively superficial disputes over which authority is legitimate. And it is why all authoritarian political theories, and the systems they give rise to, are irrational: all people are fallible, so no one person, nor any group of people, is fit to serve as an ultimate authority.