The states’ rights argument doesn’t hold up for a few reasons: 1) as I mentioned, all the secession declarations prominently featured the preservation of slavery as a reason; 2) while there had been debates over state’s right since the nation’s founding, the issue didn’t come to a head until Lincoln’s election made it appear to Southern states that abolition was imminent (which it wasn’t); and 3) the South was selective about which states’ rights they cared about. They were fine with the Fugitive Slave Act, which required that escaped slaves be returned to their owners even if they had made it to free states, which completely ignored the right of those free states to allow the escaped person to stay.