One of the favorite taunts in on-going, tense negotiations is to lambaste the opposition as childish, or not "acting like adults".
When did people get the idea that "acting like adults" in itself guaranteed successful and mature action?
In some contexts, "adult" suggests perversion, or material not fit for general consumption. If that is not the case, then what are we talking about?
I assume that "acting like adults" means taking responsibility for one's actions. It involves taking chances when a major decision has to be made. It means that people will respect the needs of the other party in negotiating a difficult compromise.
Yet the taunt "we need to start acting like adults" is in itself misinformed, blameworthy, and snide.
Let's not ignore the trite yet necessary fact that most "adults" do not act like "adults."
Let's also consider that there are some characteristics of children worthy imitating to some degree. Children are willing to be lead as well as to lead, when it becomes necessary. When they do not feel threatened, they are not afraid to share what they have. They can trust others. Adults in difficult times need to be willing to do these things.
Adults do not wait for other people to act like adults, I guess. They do not talk about it, or taunt others for failing to do so.