What do you understand by the right to national self-determination?
How has this idea resulted in both formation of and challenges to nation-states?
Right to national self-determination means seeking the right by cultural groups to govern themselves and determine their future development as a nation.
The idea of national self-determination led to the formation of nation-state. As in case of Europe after First World-War, the countries were formed on the basis of culture they shared. It helped these groups to determine their future development path and to govern themselves.
This idea is also a challenge to the formation of nation-state as it is impossible to have one culture in a nation-state. It is impossible to ensure that each cultural group could achieve political independence and statehood. Examples for the same could be the mass migrations that took place after the re-organisation of state boundaries in Europe to maintain cultural homogeneity.