I think a "government" like the UN might work fairly well. I don't think that something like the US federal government will ever work too well on a government scale. A world government has to somehow manage both the middle east and the whole area around sweeden (can't remember the name). It would have to be a very "soft" government that enforces very few things, and works to prevent and shut down any war. Also, how would it manage when two nations have conflicts with one another. Those boundaries aren't going to disappear, and while US states can get along well, no two states are really in competition with each other as countries are. Or are they? I have never heard of the possibility of two US states being in a condition where they would go to war (civil war aside)