[BroJoeK]

jeffersondem: "Let’s stipulate, for the purpose of this post, that the secession was not a pleasure.
It was still unilateral independence by known states of slavers.
You tell me, can that be morally justified?"

Well... as a connoisseur of fine English words, you know Madison's term was not "a pleasure", it was "at pleasure", which we still use today in saying, for example: the Secretary of State serves at the pleasure of the President, meaning, the President can fire the Secretary for any reason he wishes, or for no reason at all.
That's "at pleasure", and it is the ultimate justification used by secessionists in 1860-1 and defended by our pro-Confederates today.
It's the justification used when they say, "secessionists didn't need a constitutionally valid reason because of the 10th Amendment, or the laws of nature, or even the Declaration of Independence saying, 'whenever' and 'whenever' means 'at pleasure'. ".

The opposite of "at pleasure" is necessity, which our Founders used in their Declaration to justify their actions, necessity spelled out in over two dozen specifics, i.e.:

"He has plundered our seas, ravaged our Coasts, burnt our towns, and destroyed the lives of our people."

That's necessity, necessity cared nothing then about the status of slavery and our Founders went out of their way to insure slavery was not an issue in their Declaration.

By stark contrast 1860-1 secessionists made slavery the centerpiece of their "Reasons for Secession" documents, a fact often denied by our pro-Confederates today.
But the reality is: Deep South Fire Eaters issued unilateral, unapproved declarations of secession, at pleasure, for the stated purpose of defending their "peculiar institution", slavery.

from Lincoln's "Speech to 140th Indiana Regiment" (March 17, 1865)

[jeffersondem]

“Well... as a connoisseur of fine English words, you know Madison's term was not “a pleasure”, it was “at pleasure”, which we still use today in saying, for example: the Secretary of State serves at the pleasure of the President, meaning, the President can fire the Secretary for any reason he wishes, or for no reason at all . . .”

That is an interesting comment. And a purposeful distraction from inquiry.

Setting it aside for now, I'm still curios about your contention (post 1355) that distinguishing “right from wrong” cannot, will not ever include defending a slavers’ war of secession.

In your post you did include the artificial construct “1860s era” but, of course, that was not the only time slave states invoked the right of secession to separate from the empire and to go on and build a new country where slavery was enshrined in their constitution.

Point blank question: Can slave states, under any circumstances, claim the moral right to "institute new Government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their Safety and Happiness"?

If you think the answer is "no," just say no.

[jeffersondem]

“The opposite of “at pleasure” is necessity, which our Founders used in their Declaration to justify their actions . . .”

Necessity is not the opposite of “at pleasure.”

“No necessity” is the opposite of “necessity.”

At pleasure, as explained in your own musings, means:
“the Secretary of State serves at the pleasure of the President, meaning, the President can fire the Secretary FOR ANY REASON he wishes, or for no reason at all.” (emphasis added)

By your thinking, at pleasure could be a bad reason, or a very, very, very good reason. It could even be a necessary reason.

Again, necessity is not the opposite of “at pleasure.” It is one subset of “at pleasure.”

The issue, always, is who determines what is a necessity.

And you have repeatedly provided your preference. You say Abraham Lincoln, a regional candidate with 39 percent of the vote and an uneven past, was the only one qualified to determine necessity.

But our founding fathers, unanimously and unambiguously, placed in black and white a better method than one-man rule.

I think you know where I'm heading. If you want me to spell it out, I will. And I will not have to use secondary sources to do it.