well first of all i think you are equating society and territory, but even so, a society/territory is not akin to a book club. if there is only one club, that you are born into, does that analogy still make sense?
if "outsiders" have no right to declare themselves members of a society -- by what principle does the society earn this right?
it seems that this principle is merely the georgraphy beneath your feet when you were born. i can think of many alternative "rationales for membership" that are much less trivial. remember modern states were born out of "patriotism". i think that is still what defends them. the insider/outsider distinction is precisely the problem.
You are right about the territory. I had a paragraph about it but deleted it :). Territory is a tricky aspect. Over time, territory changes its value. The Inka territory/society in Middle America were once the peak of evolution. Now the territory/society is not that interesting anymore. Same story for the territories we nowadays know as Egypt, Iraq or Syria. After the Oil you can count Saudi Arabia to it. The UK was much more interesting 100 years ago.
Territory is indeed a factor. But one which is volatile as an aspect how well a society develops on it.
And regards being born in a society: There is nothing stronger than the bound of a family. Why we are surprised that the societies select this as a primary membership rule. And this is universal like that in every spot of the world.
if "outsiders" have no right to declare themselves members of a society -- by what principle does the society earn this right?
it seems that this principle is merely the georgraphy beneath your feet when you were born. i can think of many alternative "rationales for membership" that are much less trivial. remember modern states were born out of "patriotism". i think that is still what defends them. the insider/outsider distinction is precisely the problem.