In that case we're all guilty of treason since the Articles of Confederation explicitly declares itself perpetual and since unanimous consent of all the states is required to change it. The Current constitution came into effect after only three fourths of the states ratified - and it was four years before all the stragglers came in. How'd they do that?
It is a mistake to confuse a sovereign action with constitutionalism or law. To secede is, by definition, to operate outside of the previous constitution and legal system. We seceded from the British Empire in the 18th century even though it was illegal to do so. We did it as a sovereign act.
That said, the tenth amendment reserves the right of secession to the states.
We must begin with recognizing that the Constitutional Convention was called after it had become abundantly clear that the Articles of Confederation were inadequate to the task of governing the several states or, as Federalist 1 put it, "after an unequivocal experience of the inefficiency of the subsisting federal government...." The flaws of the current system were obvious to the Founders.(See the Federalist Papers, especially 15-22.)
The Current constitution came into effect after only three fourths of the states ratified - and it was four years before all the stragglers came in. How'd they do that?
The easiest answer is probably the right one: the Articles of Confederation granted much more leeway to the individual states than the Constitution does, and it was only right and proper to allow each state to surrender that measure of sovereignty on its own decision, rather than by force.
In any case, the question is not how the states came to place themselves under the Constitution, but rather whether or not they had the right to leave once they had done so.
A state's vote to ratify, was an explicit surrender of some degree of state sovereignty to the Union of states, and to the ultimate supremacy of federal government where matters of multi-state concern were involved. Among other things, requiring an explicit state ratification as part of agreeing to join the union, rather obviously carries with it the burden of prohibiting a decision for dis-union.
It is a mistake to confuse a sovereign action with constitutionalism or law. To secede is, by definition, to operate outside of the previous constitution and legal system. We seceded from the British Empire in the 18th century even though it was illegal to do so. We did it as a sovereign act.
This is dizzying ... you defend secession as a "sovereign" act and therefore "legal," on the basis of its being illegal in the case of the Revolution. That is nonsensical. The Founders freely acknowledged the formal illegality of their declaration of independence, and fully expected to be hanged if they did not prevail.
You also seem to be saying that declaring a law invalid, or declaring oneself to be immune from that law, actually makes it so. The only way to validate such an action would be for the existing authorities to refuse to enforce such a claim -- which was clearly not what happened when it came to the American Revolution, or the Confederate secession.
One must expect the authorities take exception to your claim to be beyond their power -- such a claim is explicitly to invite a response. It is silly to complain when such a response is actually carried out.