By "the political," I refer to the dimension of antagonism that is inherent in all human society, antagonism that can take many different forms and can emerge in diverse social relations. "Politics," on the other hand, refers to the ensemble of practices, discourses and institutions that seek to establish a certain order and to organize human coexistence in conditions that are always potentially conflictual because they are affected by the dimension of "the political."
It is only when we acknowledge this dimension of "the political" and understand that "politics" consists in domesticating hostility, only in trying to defuse the potential antagonism that exists in human relations, that we can pose the fundamental question for democratic politics....Politics aims at the creation of unity in a context of conflict and diversity; it is always concerned with the creation of an "us" by the determination of a "them." The novelty of democratic politics is not the overcoming of this us/them distinction - which is what a consensus without exclusion pretends to achieve - but the different way in which is established. What is at stake is how to establish the us/them discrimination in a way that is compatible with pluralist democracy.--Chantal Mouffe (1999) Deliberative Democracy or Agonistic Pluralism? Social Research, 754-755.
Mouffe offers here two definitions. Her definition of the 'political' is refreshingly universal ("inherent in all human society"); it does not (unlike many Liberal definitions) presuppose democratic norms or institutions and is applicable to all societies. It does not claim that all societies are characterized by antagonism, but it is committed to the idea that is always present as a latent disposition ("potential antagonism...exists in human relations.) So, let's call Mouffe's definition of the 'political' Mouffe's First Law. Mouffe's First Law entails that antagonism is not (pace Rousseau) a consequence of social relations/institutions, but (conceptually) precedes it. (We may say jokingly that the conception of human nature is robustly Augustinian.)
The definition of 'politics' also does not presuppose democratic norms or institutions. But unlike the First Law, which one might be tempted to understand as a kind of neutral generalization (or a conceptual a priori), Mouffe's definition of politics is is an invitation to think beyond Liberalism: politics is the means (mechanisms & practices) of producing a kind of outcome/effect, that is, "a certain order and to organize human coexistence," that is, a minimal unity, and, thereby/simultaneously a domestication of antagonism. Anything that facilitates -- e.g., education, [civic] religion, propaganda, economic organization, habits of thought, etc. -- such outcomes is, by definition, an element of politics. This understanding of politics echoes Spinoza's and Hume's (recall), and so is not necessarily at odds with elements of the Liberal tradition (but can also be found in Hobbes and, going back [recall] to the Roman, Republican historian, Sallust), but it is not how Liberalism ended up being characterized in its more laissez faire strands.
To be clear: this unity is constituted by an "us/them" distinction. Politics both presupposes and generates as well as transforms and helps maintain such a distinction such that 'us' are within the shared unity, and them without. There is no unity without an outsider.
So, as Mouffe explains, given the First Law, the task of politics is to move from one kind of antagonist to a less virulent kind: she "is no longer seen as an enemy to be destroyed, but as an "adversary," i.e., somebody with whose ideas we are going to struggle but whose right to defend those ideas we will not put into question. This category of the adversary does not eliminate antagonism." (755)
Here my interest is not in distinguishing her view from (or tracing it back to) Schmitt's. Rather, I call attention to the fact her understanding of an "adversary," is actually quite demanding. There are two elements: first, it is "somebody with whose ideas we are going to struggle" and, second, "whose right to defend those ideas we will not put into question." While there is some ambiguity in what counts as struggling with another's ideas, I take it she means that with an adversary one tries to engage with the content of the ideas and try to refute/discredit them through a variety of (rhetorical, educational, argumentative, framing, etc.) techniques. The first element presupposes some interest in the adversary's views. (It need not entail trying to be fair to them or getting them wholly right.) It is easy to miss this. The second element is, in fact, quite clearly a democratic norm. It is no surprise then that "the aim of democratic politics is to transform an "antagonism" [of enemies] into an "agonism" [of adversaries]." (755)
There is, thus, quite a bit of conceptual space between an enemy and an adversary. There are going to be political cultures in which there is some unity, and in which (say) citizens (tacitly) relate to each other as an us, but in which they do not understand each other as adversaries. For, as my colleague Enzo Rossi reminded, there is a kind of (let's call it) hearing without listening: an unwillingness or incapability of struggling with each others ideas (and an unwillingness to really grant each other the right to defend those ideas) without resorting to overt violence. I am unsure if there is a term for this, but it deserves one (and I look forward to learning from my readers).
The previous paragraph is not a hypothetical scenario. Once passions are mobilized (and perhaps not only then), a certain form of mutual non-engagement (that is no struggle with the ideas of others) with fellow nationals can be normalized (through media echo-chambers, social segregation, etc.). I believe this is increasingly the the status quo in contemporary, purportedly Liberal Democracies .