If the most effective measure that humankind can take to rid itself of the threat of nuclear war is to establish a government and political system for the planet as a whole, what are the prospects for doing this? Obviously, the problems in achieving a world government are awesome. In the first place, the record of both the League of Nations and the United Nations in keeping the peace is not encouraging. When one reflects on the cultural, religious, and political differences among the countries of the world, the probability of unifying them all without the use of force seems small indeed. And if force had to be used, the cost would probably be destruction and death as widespread as in nuclear war itself.
Even if a single world government is established, what reason is there to hope that endless civil war would not follow? Established states have avoided civil war, but the words "established state" presume a relatively homogeneous citizenry and a working political system. The history of "new" states that came into being after World War II is an endless repetition of civil war and insurrection. Malaysia, the Philippines, Burma, Indonesia, India, Sri Lanka, Nigeria, the Sudan, the Congo, Angola, Ethiopia, Somalia, and so on down a long, long list -- all had civil wars or rebellions. And this does not include the wars in Korea and Vietnam, since they were as much international as civil wars. If you add the civil wars among "older" states that do not fit our definition of "established states," such as China, Cuba, Nicaragua, El Salvador, and Yugoslavia, the list almost doubles.
But in spite of this dismal historical record, the consequences if humankind continues to fight wars as it has in the past are so horrifying that even the slimmest chance of unification through some sort of world government is worth pursuing. If we understood the obstacles better we might find a way around them.