This idea is often linked to the concept of democratic self-determination within nations. While once associated with liberalism, prominent proponents of this argument nowadays tend to be conservatives like Yoram Hazony.
People across the world have different cultures, beliefs, and values. On this basis, these people can be grouped into distinct nations. These nations are organic cultural units where people share a common heritage. A world of nations is a world that acknowledges and preserves cultural distinctiveness. These provide the basis for different nations within which these values can be autonomously expressed and preserved. By contrast, other forms of political organisation like empires subordinate a variety of different groups and cultures to a single value system and erode cultural distinctiveness.
Claims that nations are natural cultural units are also dubious. Many examples exist of nations with sharp internal cultural divisions including Malaysia, Lebanon, and Ethiopia. Claims that nations preserve cultural distinctiveness are also dubious. Many nation-states make great efforts to erase internal cultural differences. Meanwhile, empires far from imposing a single set of universal standards often rely on or positively encourage cultural differentiation as a strategy of divide and rule, and to keep harmony between the various groups within the empire by ensuring none feel threatened by others imposing its values on the other. Cultural distinctiveness need not be respected if we find its values morally objectionable. Equally, other things are more valuable than cultural distinctiveness such as peace and prosperity and these are better provided by large non-national units.
[P1] Nations exist as distinct natural cultural units. [P2] Cultural distinctiveness should be respected. [P3] The best way to respect and preserve cultural distinctiveness is through creating nation-states as independent political units.
Rejecting the premises
[Rejecting P1] Nations are not natural cultural units. [Rejecting P2] It is not clear cultural distinctiveness and diversity is valuable. We might even see it as damaging in some cases. [Rejecting P3] Nations are homogenising and don't preserve cultural distinctiveness. Other forms of state preserve cultural distinctiveness better.