This raises two questions:
1. Why then did the Founders not mention secession when laying out parameters for admission, dividing into two or more new states, etc.? Why would they be so explicit regarding the incoming and division, but silent (yet implicit in your honest opinion) about the outgoing?
2. Secession is not addressed explicitly in the United States Constitution, but you present secession as not being prohibited by the document (which it most certainly is not), and then you string the implicit nature of its legality further by noting a Constitutional distinction between unilateral and multilateral secession. If you (and supporters of the act) can imply secession as a right of a state by saying its not prohibited (and supporters would also invoke the Tenth Amendment to further bolster their argument), how (without citing Article IV Section 3) can you then imply a Constitutional distinction between the two forms of secession (and I say without citing Article IV Section 3 because it is explicit on admission, etc., yet silent on secession)?
Why would the founders be so explicit in requiring the approval of Congress in every other matter affecting the status of state, why would the Constitution restrict the actions a state may engage in that could affect the interests of the other states, and then imply that a state may unilaterally leave at will without consent of all the parties affected? That is what makes no sense at all to me.
2. Secession is not addressed explicitly in the United States Constitution, but you present secession as not being prohibited by the document (which it most certainly is not), and then you string the implicit nature of its legality further by noting a Constitutional distinction between unilateral and multilateral secession.
On the contrary, I have never said that secession was prohibited by the Constitution. The Constitution is silent on the subject. Some may take that to mean that secession is prohibited, but I do not. But absent specific instructions on how to accomplish it, it makes sense, to me at least, to look at the other ways the Constitution deals with the states. States do not join the Union at will. They are admitted with the approval of a majority of the other states through a vote in Congress. Once admitted they become part of the body politic, enjoying the same benefits as the other states. They take on the debts and the obligations incurred by the country as a whole, and they accept the restriction imposed on the states by the Constitution. They agree not to enter into any treaties or compacts with foreign countries without consent of Congress. They agree not to place duties on imports or exports unless Congress approves. They agree not to enter into compacts with other states unless Congress approves. And on and on. And the one common thread in these is that such actions, if done in a unilateral manner, could have a negative impact on other states. So why should secession be any different? A state ups and leaves, walking away from debts and treaty obligations and commitments, possibly blocking trade or access to the sea for other states, ceratinly appropriating property owned by the country as a whole. Why should something as drastic as this be the one unilateral action that, by implication, would be permitted?
I don't have a problem, per se, with secession. But I believe that the Constitution is pretty clear on what states may and may not do on their own. If a state wants to leave then fine, do it in the same manner that the state entered the Union to begin with. As far as I'm concerned you can negotiate settlements on all questions of concern to both sides, allow Congress to vote approval, and then don't let the door hit you in the ass on your way out.