This is where the rubber meets the road. And as our friends 4CJ and Stainlessbanner have pointed out, this argument is anterior to all the others, and all the others, including the outcomes of the various Supreme Court cases, depend upon it.
1. As our friend has pointed out again, all the States, including Rhode Island, were indeed sovereign before they ratified the Constitution. Rhode Island, he points out, remained sovereign longer than others, while the People deliberated -- and ignored threats of retaliation from Connecticut if they didn't "git thar mahnds raht", in the ineffable line of Strother Martin.
2. Rhode Island explicitly -- and unnecessarily -- reserved the right to resume full sovereignty and secede from the Union, in her articles of ratification.
3. All the States had sovereignty, because every single State was a People, colonized, populated, and revolutionized individually and separately from all the others, and most importantly for our purposes, every State had individually and separately, and by a sovereign act taken as a People, a populus, mastering their own affairs, ratified the Constitution.
4. The People never, ever, EVER give up sovereignty, in the United States.
5. The Southern States therefore had the right, which they did not, anywhere in the Constitution, surrender, to gather together in conventions as populi, as Peoples, to reconsider the Union -- and to withdraw from it, in a series of acts of sovereignty over which the other States and Peoples had no right of supervision, much less approval, any more than they had the right, which Connecticut thought they did, to compel Rhode Island's ratification of the Constitution.
6. Please re-read No. 5 slowly, for comprehension.
7. The argument advanced here, that secession is legal only if it is approved by the other States, confutes itself. Let us consider it.
Suppose Florida, citing language and cultural differences, wanted to secede and join the Antilian Confederation. Suppose Florida took her case to the Union for "approval", as the Unionist apologists, who favor the "Suitors of Penelope" theory of ratification, indicate she should.
To whom does Florida apply? How can Florida apply? Florida has no sovereignty, and is a subordinate political unit of an undivided United States. Does Florida apply to Congress? Does Florida ask the other States to go into Convention to consider her appeal? Does the Florida legislature do this, or the governor? They can't, they're bound by the Supremacy Clause. They can't touch it. So Florida must convene a State convention, and pass a plebiscite for disunion, and submit it.......to whom?
What constitutes a sufficient response by the other States, under the Suitors of Penelope Theory? Suppose 40 States go into convention (remember, their state governments can't touch this either -- they're bound by the Supremacy Clause, too) and approve, five States convene and say no, and the other five don't even bother to hold a convention or reply? What then? And what does the United States Government do? Is the United States Government a party to resolving this question? Careful with your answer -- it'll reflect on Lincoln. Does the President of the United States simply forbid Florida to leave the Union, relying on his Executive powers to see that the laws are executed? That's what Lincoln did. But in that case, the Government is talking down to the People -- and therefore the People are not sovereign, but the Government is sovereign instead.
And that, Sir, is Lincoln's Revolution.
Lincoln may have felt himself justified in making that revolution -- as he himself said about Robert E. Lee, it's always the best men that do the most damage -- and he may have been utterly convinced that he had to square a circle, in order to eliminate slavery, which he saw as a blot on America's escutcheon that undermined our exemplary role in the world. At least that is what Donald Douglas, in Lincoln, says was Lincoln's primary motivation in eliminating slavery -- and I believe him. But by ending slavery the way he did, he also ended the American Experiment in terms congenial to the cynics of the Old World, and gave the lie to the Founders, who said that a People could rule itself, and not be ruled by men of power.
8. Therefore, the Southern States were within their rights to withdraw from the Union when they saw that their differences with the majority in the North were irreconcilable, and that the champion of the anti-Southern faction had emerged triumphant in contol of the apparatus of the United States Government. They were within their rights to secede, and by overthrowing them by armed violence, Lincoln enthroned Government as the Sovereign over the People, and made the People the plaything of politicans and generals. In so doing he laid the groundwork for National Greatness politics, the Gilded Age of access capitalism and government by pocketbook, socialism, and eventually world empire.
In your view the states seem to be like atoms free to combine and separate, but unbreakable in themselves. But the nation is more than a molecule to be dissolved chemically. There is a common national heritage to be disposed of when nations are dissolved, and doing so can be very problematic. It's also simplistic to assume that the states are the people. A working federal system allows for the majorities and minorities in the nation and the states to have their say. Secession at will doesn't incorporate the same safeguards for all interests.
I don't think there are any easy formulas to solve the problem. The founders could have resolved the problem by including a means of dissolution of the union in the Constitution. That they didn't means that subsequent generations must procede with caution and not presume answers that aren't present in the Constitution or acceptable to all concerned parties.
As for your example, I'd imagine a lot of Floridians would object to joining an "Antilian Confederation." One can imagine a convention called in Miami that does not at all reflect the views of North or Central Florida presuming to speak for the whole state and take it out of the union. One can imagine other Floridians taking objection, questioning the legitimacy of the convention, and trying to form their own loyalist state or states. Secessionists forces will assert their own legitimacy and deny that of their opponents. Violence is likely. That is why dissolution of the union is such a grave and ponderous matter. Simply arguing that "states" can leave at will is in the end a recipe for war. There has to be much negotiation and there has to be unquestioned procedural legitimacy.
Now we have had much more experience with nations and empires breaking up and new states seeking independence. The general lesson seems to be that patience and persistence win out in the end. In most circumstances the best path is not simply to declare independence and fight a war, but a long process of political, legal, diplomatic and propagandistic activity. If secessionist leaders had taken that path, they would have gotten their nation or nations. We would be the worse for it, though their own generation would have been spared great losses. Unfortunately, Southern political elites were mesmerized by the idea that they were struggling against some tyranny or oppression, rather than just trying to get a divorce. Therefore they had to make the federal government of their time out to be some sort of oppressor to be resisted by any means -- an evil misrepresentation that would poison the situation and have evil consequences. The secessionists were also misled by the dubious idea that they could simply walk out at their own will. And they were also in a rush to set up their own new nation or confederation and get what they thought was their due of the national spoils.
I'm not going to go to great lengths to malign the Confederates. They were Americans and they were fighting for their own conception of freedom. But justifying or glorifying them is another matter, and excusing them while vilifying their opponents is even further out of line. They joined a rather dubious, simplistic, and self-serving view of the Constitution to defense of a particularly heinous institution and garlanded their rebellion with high-flown rhetoric. They replaced constitutional government with violence and buried the old Republic. I might have had more respect for them if they'd shown more respect to our national venture and history and hadn't simply given up on it. That they were willing to throw away the country when, through their own folly, they lost an election, makes them unacceptable as a model for republican virtue. That they chose to cloak themselves in the garments of the Founders makes them more repugnant.
You may be moved by the sufferings of the South in the war. I am too. It is a moving story. But that the leadership wasn't prepared to act patiently and "suffer" the inconveniences of constitutional politics makes them not worthy of respect in my eyes. They had channels to get what they wanted within the system or by gradually separating from it. But they were impatient with the workings of a sucessful system and resolved to get out immediately, even at the cost of smashing it. I'd say that there was something about the idea of secession at will that made it likely to be used for trivial or wrongheaded purposes, but if you believe in secession as a right or as something desireable, you might reflect on the way that the idea was wasted by the cause these men put it to.
It sounds nice to some to blame Lincoln for the fall of the "Old Republic" and throw the Guilded Age corruption at him. One can't wholly absolve him of blame at least for the latter. But secession destroyed the older Republic. Whatever came afterwards would be new and different and very much a let-down.
I am reminded of Faulkner's comment that inside of every Southern boy there is a place where it's always July 3, 1863 with the fate of the South in the balance. Some people believe that but for Lincoln it would always remain 1860 with the same degree of freedom and scale of government that existed then (too often conveniently forgetting the degree of unfreedom). But time and history do bring changes. Forces similar to those working in our own world would have their effects in the parallel secessionist universe. Tensions and conflicts wouldn't stop. What's ironic is that those who advocated truly radical change -- the breaking of nations -- are seen by some as stopping the clock in 1860.
"And that, Sir, is Lincoln's Revolution."
That's it in a nutshell isn't it? Excellant.