Ask HN: Should having just political borders and no social borders help?
In ideal situation I would have said that removing all borders will reduce major conflicts. But we don't live in an ideal world. The "ruling class" will not want to let go of the borders for political reasons. But removing social borders(i.e. allowing people to move across the world unhindered) will help disconnect the masses from the classes. Most of the major wars are started by the classes and millions from the masses die due to that. If the social borders are removed, it will be very difficult for the classes to drag the masses into conflicts due to political reasons/borders. In that case the wars are then relegated to a very small section of the society and hence will be limited and of smaller duration.
with political borders comes jurisdiction, so even if social borders are removed there won't be problem of criminals going unpunished. We do have present structures such as local justice system, international courts etc in place to tackle those issues.