I think it would work. It is kind of a broad question - many states that are bad places work. I don't think that a world governments would be desirable. It seems that it would create a power structure with an incredible potential for abuse. If we are to have governments, it is best that they are small and fragmented. At least this way some may be able to provide a safe haven, or a check on unrestrained power. For example, if a state becomes abusive its people may flee elsewhere. If the entire world were one state you're basically stuck with what you have got. This is already a problem due to immigration laws and borders, but it would be absolute in a single worldwide government. I also feel like there are many communities who might want to live in very different ways. A local community may be able to agree and live in harmony with social rules and mores. But if we tried to apply one standard of law to the entire world I think many people would not be content with laws.