You speak as if secession were an ingrained maxim of the Constitution. The checks and balances prescribed by the Constitution are quite explicit. The argument you seem to rest on is solely the tenth amendment, which maintains that any powers not granted in the Constitution are reserved for the States or the people.
However, though the Constitution doesn't provide means to leave, it does give power to the national/federal government to fight insurrection. What's the difference? A state would have no power at all, lest it had that one. We may assume that, at the very most, a state may leave through Constitutional amendment. That would, of course, require the approval of the other states. And why not? Much of the infrastructure and federal taxes were applied to the each state. In addition, even as a separate entity, the state(s) would still reap the benefits of a strong neighbor, but without having to financially support it. What a bargain!
I don't think my argument relies on a slippery-slope fallacy, but is instead simply begging the question. Even if was a logical fallacy, though, that doesn't necessarily mean it is not true (any assertion that it was necessarily not true based on a fallacy is guilty of a post hoc ergo propter hoc fallacy). The reason I don't think it rely on that particular fallacy is this: I wasn't offering a certainty, but a possibility, and it was based on the logic of the South. If I no longer approve of what the state does, then why can I not leave?
If all we're talking about, after all, is a social compact, then why cannot I just withdraw from it, just as the southern states said they could withdraw from the Union? Could they coerce me to stay and pay taxes? On what basis? Why do they have power over that land or me? Should I not be free to enter or leave a social compact?
Perhaps one thing does not necessarily mean another, but you have failed to show how it doesn't. Therefore your argument (to me at least) is only an assertion. Forgive me if I've missed your reasoning elsewhere. It's a long thread.
I speak of it in this case as an assumption because the holding of that assumption must occur first before I can assess the arguments of degree pertaining to that assumption argued by The Lincoln. It is in this light that I note, holding secession to be constitutional, that The Lincoln's slippery slope about it was not a logically valid or expected situation.
However, though the Constitution doesn't provide means to leave, it does give power to the national/federal government to fight insurrection.
That it does. I would argue that the act of insurrection though generally pertains to the common concept of insurrection - an attempt by a band of individuals to overthrow the existing government. That says nothing though of an act by legitimately seated parts of that government from taking legislative action to separate their own portions away from that government while permitting it to exist in the remainder uninterrupted.
We may assume that, at the very most, a state may leave through Constitutional amendment. That would, of course, require the approval of the other states.
Such an assumption is not necessary. The reason for this is self evident, that being that the ratification of the constitution by an individual state did not require approval of the other states for acceptance. Rather, it was voluntary. As Alexis de Tocqueville noted, for a voluntarily joined union to prohibit voluntary exit from it is to exert a force contrary to the nature of that same union's voluntary origins.
And why not? Much of the infrastructure and federal taxes were applied to the each state.
That they were, but they were also paid for by taxes collected in each of the states. It is not as if the seceding south "stole" the belongings of the north by simply claiming for themselves properties within their borders. For that to be so, one must hold that the entire properties of the 1860 federal government were in fact exclusive holdings to which only the yankee states were entitled. Such is nonsense since the south paid taxes too and in many cases provided the property and resources for the construction of those sites. When The Lincoln responded to secession by claiming all those southern properties for the "union," he was in reality asserting a claim that they were the exclusive domain of the northern states regardless of where they were located or the southern contribution to their purchase.
In addition, even as a separate entity, the state(s) would still reap the benefits of a strong neighbor, but without having to financially support it.
Do you suggest then that nations of the world be required to pay tribute to regional strengths in their proximity? And all that goes without mentioning that the south proved itself to possess military capabilities and strengths of its own that fended off the might of that same neighbor on inferior resources for four long years.
I don't think my argument relies on a slippery-slope fallacy,
When one asserts that the acceptance of state secession will necessarily lead to city, town, and neighborhood secession, that is a fallacy of slippery slopes. It is a fallacy as the connection is not necessary and in fact a condition exists to differentiate between state secession and other secessions.
Even if was a logical fallacy, though, that doesn't necessarily mean it is not true
A request to prove a negative is itself another fallacy. Accordingly your argument fails both in the initial slippery slope and in its request of a negative proof.
any assertion that it was necessarily not true based on a fallacy is guilty of a post hoc ergo propter hoc fallacy
No. Post hoc is a fallacy of causality. An assertion of a negative proof is a fallacy of conclusion based upon a previous fallacy of negative premise.
I wasn't offering a certainty, but a possibility, and it was based on the logic of the South.
Possibilities are fine, but do not carry much weight as an argument. On a similar note, I could legitimately state that it is _possible_ the sun will not rise tommorrow. But that does not lend any reason per se to the assertion that the sun will not rise tommorrow, nor does it adequitely establish that the possibility of the sun not rising tommorrow should be reason to act against that possibility.