But that's not what the 10th Amendment says. The word 'specific' isn't in there so there is no reason why implied powers should be excluded. Look at the document as a whole and look at powers already specifically assigned Congress and specifically denied to the states. Congressional action is required for everything affecting the status of a state. Everything from becoming a state in the first place to the most minute change in borders. Nowhere does the Constitution allow a state to act in an arbitrary manner where the interests of other states might be involved. Why would arbitrary secession be the one arbitrary act affecting the interests of other states that would not be allowed? It makes no sense.
The Constition must be looked at as a whole because the sum of its parts is more encompassing than the individual parts. If, as you say, the government is not allowed any powers not specifically mentioned in the Constitution then how can we have an Air Force? The Constitution allows for an Army and an Navy, nothing else. By your definition then only states could raise and maintain an Air Force. But because the Constituion calls for providing for the common defense then the power to maintain this particular branch of the military is implied. So to for arbitrary secession.
As for opting out of the Union, I have never maintained that the United States was meant to be permentant. I firmly believe that a state or states have the right to leave the Union so long as they do it within the framework of the Constitution. It was the arbitrary manner of the southern action. Had they left with the approval of the majority of Congess then I would have applauded their action, wished them well, and let them go on their merry way. But they didn't. Instead the started a Civil War. They fought a war of rebellion. They fought a war to maintain their peculiar institution and because they believed majority rule and states rights were fine, so long as they were the majority and that the states rights that were trampled on were someone elses. They were in the wrong and they paid the price for their actions.
...Had they left with the approval of the majority of Congess...
First, the States, via the Constitution, allow the Federal Government to act.
Second, if a State requires consent of the other states to leave, the State has no right at all, as the other states will never deem their actions, which give rise to the first State's desire to leave, as offensive.
Third, there is NO PROVISION THAT REQUIRES A STATE TO GAIN THE CONSENT OF THE CONGRESS TO LEAVE THE UNION, THEREFORE THAT REQUIREMENT DOES NOT EXIST CONSTITUTIONALLY. PERIOD.
Fourth, while you deem the south's actions "arbitrary" the southern legislatures evidently did not - they voted to leave. Hence, you prove my second point to you. "Arbitrary" is evidently in the eyes of the beholder.
The legitimacy of Secession is a great litmus test on whether an idividual believes our rights emanate from our Creator or from the Government.