[phi11yguy19]

Slavery caused secession.

No more so than it caused the union since it was there from day one of the declaration, day one of the articles and day one of the constitution. Slavery was there all along, so it's as naive to say it "caused" secession as it is to say it "caused" the union in the first place.

In 1789, those who ratified the Constitution acknowledged that despite their differences, they reserved enough sovereignty in their states to keep the new central government in check beside the States. In 1860, a man was elected who wished to change that and have the central government reign supreme over the States. Slavery was a constant, but that was the variable, and that was the reason for secession.

Once the compact to form a common government that treated all states equally was violated by that new governemnt, the states had every right to retain their sovereignty and try again on their own. Those principles were enshrined in the declaration in case you missed them.

[Sherman Logan]

Once the compact to form a common government that treated all states equally was violated by that new governemnt

This would actually be a decent argument if the newly elected government had actually performed some action that egregiously violated state equality, and this action had then caused secession.

In actual fact, of course, secession happened many months before the new government took office, much less took unfair action against some states, and was in response to the mere election of a president the seceding states did not like.

[Sherman Logan]

In 1860, a man was elected who wished to change that and have the central government reign supreme over the States.

On what actions or words of Lincoln's (in 1860 or before) do you base this extraordinary claim? What had he said or done that would have led southerners to believe this?