For Habermas, it is not only desirable but also possible to establish a consensus among the participants in the event of communication: and it is logically possible to organise a social formation on more rational terms, through the discursively agreed consensus. Lyotard associates such consensus with the end of thinking, and (rather like Adorno, in fact) suggests that such consensus would be merely formal, a means of covering up injustice under a veneer of justice. In a debate with Rorty - who shares with Habermas a faith in some kind of 'conversation' - Lyotard indicates that there is a 'soft imperialism', a 'conversational imperialism at work in the drive to establish consensus between participants in a dialogue. Only if we respect - and stress - the heterogeneity of language-games will we save the possibility of thinking. In short, this means that it is only in the refuse of consensus and in the search for 'dissensus' that we will be able to extend thinking, to allow it to be shocked into the new, the (chronological) postmodern. Consensus is a means of arresting the flow of events, a mode whereby eventuality can be reduced to punctuality; it is a way of reducing the philosophy of Becoming to a philosophy of Being. The modernist assumes that it is possible to pass from Becoming to Being; the postmodernist believes that any such move is always necessarily premature and unwarranted.
Politics, as we usually think it, depends upon a consensus; most often, of course, such consensus articulates itself under the rubric of 'representation' (a category which has already come under pressure in its aesthetic formulation), in which there is at first an assumed consensus between representative and represented, and secondly the possibility of consensus among representatives. This is bourgeois democracy, hardly a democracy at all. In place of such politics, it might be wiser to look for a justice. Justice cannot happen under bourgeois democracy, which is always grounded in the tyranny of the many (and even, of course, in many 'democratic' systems, on the tyranny of the few - on the hegemonic control of thought exercised by few who mediate the norms of social formation). We can no longer subscribe to any such totalising forms; but we can address the instance, the events, of justice.
Here lies the basis of an ethical demand in the postmodern, a demand whose philosophical roots lie in the work of a thinker such as Levinas. We must judge: there is no escape from the necessity of judging in any specific case. Yet we have no grounds upon which to base our judging. This is akin to Levinas:

I have spoken a lot about the face of the Other as being the original site of the sensible. … The proximity of the Other is the face's meaning, and it means in a way that goes beyond those plastic forms which forever try to cover the face like a mask of their presence to perception. But always the face shows through these forms. Prior to any particular expression and beneath all particular expressions, which cover over and protect with an immediately adopted face or countenance, there is the nakedness and destitution of the expression as such, that is to say extreme exposure, defencelessness, vulnerability itself. … In its expression, in its mortality, the face before me summons me, calls for me, begs for me, as if the invisible death that must be faced by the Other pure otherness, separated, in some way, from any whole were my business.

The face-to-face implicates us in a response, in the necessity of sociality. We must behave justly towards the face of the Other; but we cannot do that according to a predetermined sytem of justice, a predetermined political theory. The Other is itself always other than itself; it is not simply a displaced Identity in which we may once more recognize and reconstitute ourself. The demand is for a just relating to alterity and for a cognition of the event of heterogeneity. In short, therefore, we must discover - produce - justice. It is here that the real political burden and trajectory of the postmodern is to be found: the search for a just politics or the search for just a politics.