There’s a saying in linguistics: “A language is a dialect with a flag and an army.”
The field of Linguistics does not actually define what is a “language.” Linguistics definitely has the concept of a dialect, and can discuss whether two groups of people speak the same dialect or different dialects. It has concepts of things like mutual intelligibility, i.e. can native speakers of two dialects understand each other. But the idea that two dialects are part of the same “language” is a question that linguistics entirely cedes to the field of politics.
So, the answer to your question: China considers itself a single political unit, and they place a high value on considering themselves unified. France, Italy, Spain, and Portugal consider themselves distinct political units from each other, and modern Italy considers itself distinct from the Roman empire.
It’s also worth noting that people from different regions in Italy sometimes can’t understand each other, because dialects of Italian have a very large spread. Again, they’re considered the same language because Italy wants to perceive itself as a single unified cultural entity.
Were one of these regions of Italy to become independent, it’s likely they would consider their dialect to a language over time, although that process would likely involve doubling-down on the regionally-distinct features of that dialect, and probably having a distinct literary tradition as well. Something like this [already happened](https://en.wikipedia.org/wiki/Norwegian_language_conflict) when Norway became independent of Denmark.
Latest Answers