I'm sure virtually everyone agrees that people live on the Isle of Wight, but in Ireland.
Apparently the usage depends somewhat on physical size, but that can't be the whole story. How exactly do we decide which form to use? And are there any really glaring 'outliers' that don't fit the normal pattern?
LATER - I must just add that the most uncertain case I've found so far is The Falklands. Most people go for in there, but a substantial minority (about 1 in 3) opt for on.
In my experience, this is often based on whether one is speaking of geographical versus political locations, and also the context of what you're saying. You would be "on" an island or continent or planet, but you'd be "in" a country or city or region.
So:
One would live in England, China, Canada, New York City, North America. (Political locales.)
One might be located on the British isles, Manhattan Island, on the continent of North America, the planet Mars. (Geographical locations.)
It's kind of fuzzy, though, because I've heard of people living in Africa or Antarctica. Can anyone think of exceptions to this—this is English, of course there will be some—or help clarify further?
Edit: Wow, that's quite the discussion going on in the comments!
I'm convinced that while this answer is an extreme generalization, it does seems to serve as a good starting point, if nothing else. Like everything else in English, there are no absolutes.
I live in Manhattan. I also live on Long Island. Bear in mind that Manhattan is much smaller than Long Island.
Would you live on the Napa River Valley or in it? I think it may be more related to the containment of the item/object in question. For example, I can stand on the ground, atop a rock, but in a hole, river, or valley. Similarly, fish live in the ocean, but ships float on it.
In this case it might be more appropriate to think of in as within. I'm not going in the door, I'm standing within the walls of the house. The shortened version of that being, "I'm standing in the house."
The same could apply to continents and why the accepted answer notes that some may make reference to "living in Africa." This is because they are within the borders of the continent of Africa.
It also depends on the physical geography. You live in the Dales (valleys) but on the Moors.
You live "on" a hump, but "in" a bowl. Once something is big enough that it becomes larger or more irregular (no longer expressible as a single characteristic) than a bowl, you change from "in" to "on."
Therefore, "in" Africa or other continent. "In" Ireland. When you express the concept of a country as an island, you emphasize it standing out of the water and it becomes a hump, and you change to "on."
This can apply in the plural, so The Falklands can be either multiple bumps, or one political entity.
I believe this generalizes all the other comments made, even the one about Earth - a bump in space.
Listen to the sound of "on the British Isles" and "in the British Isles" and you will be able to discern the isles rising out of the sea in the first case, and being an indistinguishable entity in the second.
Perhaps it's not merely the size that matters, but also the shape. For example, the word on seems to flow rather naturally when talking about with peninsulas; I know people from Massachusetts rarely use the preposition in, instead opting for on:
- He was born on Cape Cod, then moved away when he was in his twenties.
- We'll be vacationing on the Cape next summer.
- George was born in Cape Town, but now he lives on Cape Cod.
- Well, my goodness. How often do you see a bear on Cape Cod?
I don't know if there's a hard and fast rule that will always work. Sometimes local culture might favor one preposition over the other.
