It is a philosophical form of digestion.
digerere "to separate, divide, arrange," from dis- "apart" + gerere "to carry"It is critical.
Latin criticus "a judge, literary critic," from Greek kritikos "able to make judgements," from krinein "to separate, decide" ... [see also crisis:] from PIE root *krei- "to sieve, discriminate, distinguish"The philosopher qua diplomat doesn't occupy the position of a judge empowered by Reason or Nature. However, distinction, separation, sifting - all that needs to be added to these qualities is a commitment to negotiation and a deferment of de-cision - a reluctance to cut the thread of debate - and we have diplomacy.
Diplomacy is only 'post-critical' inasmuch as it departs from the vulgar modernist and postmodernist versions of critique that sought to destroy their opponents by enveloping their opponents' being in their own concepts with no remainder, leaving no possibility for engaging with objections. In many ways this departure is actually a return to older forms of philosophical, dialectical discourse that were built upon conversation. The major difference from these older forms, in principle, is that there is no Nature or Reason to appeal to, to slap down as a 'trump card' so as to prematurely close the conversation. But, in practice, the classic dialogues rarely resorted to such vulgarities. Latour has a theory/practice problem of his own.
Opponents in diplomacy are not antithetical in any metaphysical sense. Indeed, any diplomatic 'summit' will have many interested parties, those parties will have complex alliances and ententes as well as disagreements and feuds. But not all forms of dialectics have demanded that their terms be placed in such strict straitjackets as thesis/antithesis. Diplomacy does not seek synthesis, it seeks settlement. But then not all dialecticians have been pursuing the end of history.
A thing is what it does. Diplomacy is simply a reformed dialectical critique imbued with an ethos and aesthetic of compromise, respect and coexistence. A rose by any other name...