Imagine a situation (from experience in a small town in Southern France):
Person A announces “I do not speak to person B” which, in French, might be reported by A to X, Y, or Z, as “On ne se parle pas.” “On” here is an indefinite pronoun often used in French for “we.” The declaration constitutes a community of A, B, X, Y, Z with the rule “A/B do not speak when they encounter each other.” The rule is both description and prescription, or perhaps more precisely differentiated instruction about the meta-pragmatics of an interactional style.
NotSpeaking is a complex speech act, and a trigger for further speech acts.
NotSpeaking requires instruction since, everything else being the same, it is performed at a moment when the two could and should speak, as, say, when walking by each other in some parking lot. In rural Southern France, at the turn of the 21st century, such moments start with an expression of acknowledgment that the encounter has started (smile, re-organization of the body, etc.), possibly preliminaries, then “la bise” (three “air kisses” on alternate side of the head with no body contact), and then either developments that might last very long, or else a brief comment about being in a hurry, leading to various closing statements about, say, “having aperitif before we leave.” NotSpeaking, as speech event, involves turning away of the head at the time when the expression of acknowledgment should have appeared (or other bodily movements as, for example, turning away into a side street). NotSpeaking ends after the two bodies have passed and return to their earlier state.
As Bourdieu explained in one of his best passages about ritual insults in the Mediterranean ( 1977 : pp. 10ff), Maussian gifts  (of which NotSpeaking is a peculiar case) do place obligations on both participants but the response is not automatic. Much is involved. For example, one or the other of the party might make an exaggerated display of greeting by directly looking at the other and saying something like “Bonjour!”, perhaps with a smile. In this case, not NotSpeaking may actually be an insult, whether in intent or in subsequent assessment. In any event, the field is very well organized indeed for what is definitively hard work!
In brief, NotSpeaking happens within what has also been called a “community of practice.” But this is not the nice, cosy “community” of Wenger  (1998). It is a dark place as many, in the Summer of 2016, have found, whether in Paris, Nice or other such sites of interaction and political violence. I prefer to us the work “polity” for the groups that emerge as someone or other starts doing something to others that what was not until then part of their “normal” but now becomes inescapable. One cannot make war by oneself, and one cannot not respond to acts of war. Anthropologists will have to think further about this.
One way to start is to wonder about the emergence of temporary polities when people become significant to each other (whether in love or war). The question of emergence does lead to questions about beginnings and ends, as well as questions about participation. NotSpeaking may start when one of the protagonists decides not to speak to the other the next time they met. And it may be that this next time is when B finds out that A does not speak to him anymore—and that may be the “start” for B. One could even look for the instructional moments when A asserts to B, in body movement if not in words, “I do not speak to you anymore” (or the reverse as these things do change). Conversely, the actual performance of NotSpeaking can be said to start when the two notice each other and to end a few seconds later. What is central to me here is that NotSpeaking is specific to particular persons at particular times and requires the setting up of the encounter as a NotSpeaking. Not speaking to billions of strangers is not relevant here. Only NotSpeaking to a non-stranger is relevant (whether the non-stranger is an erstwhile intimate, or an erstwhile total stranger). NotSpeaking, at the turn of the 21st century, in Southern France, is a syntagm that inscribes something in history.
There may be a way of thinking about the emergence of a new polity in history (or the re-organization of an old polity) that I have never seen used in anthropology. It would involved borrowing from physics what is called “termination shocks.” I learned about those a while ago in an article in Discover Magazine about Voyager 1  entering interstellar space. Termination shocks are ubiquitous (check you bathroom sink where you can make one by running water hard into it). NotSpeaking, (making war, falling in love) similarly arises in the interaction between contradictory forces that makes something very real: a boundary marking different kinds of normal, and difficulties when crossing the boundary. NotSpeaking catches people who may be hurt by it. And then its effects fade into inter-communal space where the tiny drama can be safely ignored.