<p>In this paper, we present a hypothesis: ‘<i>extension</i> = <i>consistency</i> + <i>preferences</i>’. It implies, on the one hand, that an extension of an argumentation framework under one of Dung’s standard semantics consists of arguments which are mutually consistent and on the other hand, that the extension is preferred to any of the non-extensions with respect to a certain relation based on some argument preferences. We propose a way of comparing consistent sets of arguments on the basis of argument preferences, which is similar to that widely used in structured argumentation frameworks for inferring the relative strength of arguments from an ordering over rules or premises. Under some constraints, i.e., when the attack relation of an argumentation framework is symmetric, when the given preference relation is strict and total or when we gain argument preferences only from the asymmetric attacks between arguments, the best sets of arguments with respect to the democratic relation exactly coincide with the extensions under standard semantics. Therefore, such a relation makes it possible to integrate two roles of preferences in preference-based argumentation frameworks. Furthermore, the relation enables us to propose a so-called preference-based semantics, in which argument extensions are identified according to the relation taken from asymmetric attacks between arguments. For example, stable extensions of an abstract argumentation framework coincide with the best sets among the maximally conflict-free sets of the framework with respect to the proposed relation.</p>