Check out the remarkable thing President Obama said Tuesday about Puerto Rico. In his speech, he stated (regarding the island's future as a state or as an independent country), "When the people of Puerto Rico make a clear decision, my administration will stand by you." That might sound reasonable at first, but imagine Lincoln saying, "On the matter of whether to stay in the Union or leave, when the people of South Carolina make a clear decision, my administration will stand by you." Uh, no... Lincoln would never have said that. In fact we fought a war because Lincoln wasn't so big on local governments determining their status on their own.
Don't misunderstand—I'm not saying Obama is right or wrong. Heck, I'm not even saying Lincoln was right or wrong. My only point is that these guys are diametrically opposed on the notion of self-determination.