Obviously the thought of world governance brings up ideas of tyrants restricting liberties via socialism and communism. What if instead of these systems, a cooperative world government was in place whose only agreed upon role would be to strictly enforce a well written constitution, such as something like the US Constitution?
To me, the main problems would be voter fraud, a federal reserve type monetary system, big tech monopolies and also a sense of complacency amongst communities.
If by some magic (perhaps blockchain technologies) these problems could be fixed, I don't see how a world government, or a world constitution would be a bad thing.
I would love to know others thoughts about this
A republic in which countries come together similar to how states in the US come together could theoretically work, but over time it would suffer from the same issues the US is currently facing, and those issues would be on a larger scale.