Why does China get tetchy when Taiwan calls itself "Taiwan"? Robert Maxwell

Let's say that the United States has a civil war in the near future. The losing side flees to Hawaii and declares Honolulu the "provisional capital" of the United States. Meanwhile, the group in actual control of the continental U.S. - we'll call that the American Republic for short - claims sovereignty over all areas claimed previously by the U.S. For some reason, however, the American Republic cannot (or chooses not to) use military force to cross the Pacific and invade Hawaii. Perhaps they don't have the naval capacity, perhaps other borders are threatened and they can't divert the troops, perhaps other countries are potentially threatening an intervention. Who knows - the point is, there's a rump US government in Hawaii and the mainland is controlled by former insurgents under a new government.

Neither the US Government or the new American Republic government see Hawaii as the nation - Hawaii is just the only area in which the former US Government is able to exercise authority. To both governments, Hawaii is an integral part of the United States as a whole. Both sides claim rightful ownership of the whole, but it's only a question of actual occupation.

Now, imagine some decades later, people are referring to the US Government in Honolulu not as the US Government, but the Hawaiian Government. That makes things... complicated. Hawaii is not an independent state under this system - it's a constituant part of a government that just happens to be the single small part that that government occupies. It's still, theoretically, a state subsidiary to the US Government. Neither side is taking the position that Hawaii itself is an independent and sovereign state - it is, and always will be (in their mind) a part of the US.

So now you go onto Zhihu (Chinese Quora) and you see that Xiao Ming has just asked why don't those silly Americans just stop calling Hawaii the United States. It only owns Hawaii, anyway! Just call it Hawaii!

Well, but... legally speaking, if you do that, you're asserting that Hawaii isn't actually part of the US, but is an independent state. In effect, even though Hawaii is the only remnant US State, it is seceding from the Union. And since the American Republic's claims are based on the ownership of the former US Government and include Hawaii, you're also declaring that you don't recognize the claims of the American Republic on Hawaii. Legally, in the mind of the American Republic, this is a declaration of secession from their country, too. And whereas they were sort of willing to overlook the irregularities of the situation before, outright secession has to be quashed.

That's why China gets tetchy, basically. Even though we colloquially call the ROC "Taiwan," the formal name is important, legally. In informal speech, whatever. But when Taiwan begins calling itself Taiwan, that's an assertion of political status outside the status quo of "we both agree Taiwan is technically under the government of China, we just don't (technically) agree which government is the right one." Instead, it's almost the intro to one of China's bugaboos - the idea that Taiwan will claim to no longer be the ROK, which would legally imply that Taiwan is rejecting all claims to control by a Chinese government, and hence that the province of Taiwan is attempting secession from China.

It sounds insane and it sounds like it's a really unnecessarily persnickety thing, but there's a ton of legal power in a name.