I would say that the threshold is at least collections of states, and I would also say that a single state ought to constitute such a threshold. A greater than 50% majority of one major city probably does not constitute such a threshold, and I would suppose it must depend most on a sufficiently large enough section of land and populace so as to constitute a somewhat self sufficient state.
In order to assert an independence, a populace must be capable of an independence, meaning they have sufficient wherewithal to manage their own affairs as a nation must be capable of.
Does this not sound reasonable to you?
Ah, then you're a Declarationist, which puts you at odds with Strict Constructionists like Scalia and Bork. Interestingly, Lincoln was also a Declarationist, stating that the "All men are created equal" phrase justified his pre-election position of limiting slavery and wartime efforts to abolish it altogether. Welcome to the yankee side.
Recognizing that one authority is derived from another does not make you an explicit advocate for the premier authority. I recognize and acknowledge that the Declaration of Independence, based on the philosophy of natural law, is of higher legal and moral authority than is the US Constitution, which is based on an agreement of a majority of representatives of various states.
I also recognize that despite explicit words to the contrary, the founders had no intention of applying that natural law concept universally. Indeed the very man who wrote the document kept slaves till his death.
I attribute his usage of this statement as an effort to dress up and make more noble sounding a document which never had any intention of doing what it's words claimed.
It was lofty rhetoric of no actual validity. Nor could it have been agreed to had the people who signed it believed that it would have applied to slaves. They took the flowery language as symbolic and applying only to themselves, not as an actual legal agreement to abolish slavery.
Lincoln did not actually believe the Declaration of Independence applied to slaves. The conduct of the founders demonstrates this conclusively, yet Lincoln merely used the words as a justification for an extreme liberal interpretation of the document to mean something far beyond that which was actually intended by those who wrote and ratified it. It is the same sort of "living document" crap that Liberals have been doing all of the last century.
Wringing out new, unintended meaning from written words is an old tool from the Liberal tool kit.
Lots of counties could feed and support themselves. Do they have a natural right of self-determination? At the same time, I doubt, say, Rhode Island could support itself. Do they not have the right?
More rubbish.
It's certainly true that Lincoln's opinions evolved over time, but Lincoln's parents were abolitionists, and there was nothing in Lincoln's history to suggest he didn't sympathize.
Politically, of course, abolitionism was impossible even as late as the election of 1860 -- it was not on the ballot!
What was on the ballot was restricting the expansion of slavery into the western territories, that was Lincoln's position and it's electoral victory was the immediate cause of South Carolina's declaration of secession.
In time the Civil War changed everything, and when opportunity presented, Lincoln first issued the emancipation proclamation and then sponsored the 13th Amendment.
In order to assert an independence, a populace must be capable of an independence, meaning they have sufficient wherewithal to manage their own affairs as a nation must be capable of. Does this not sound reasonable to you?--You, in #248.
Reconcile?