This notion that we govern ourselves the way we do because of Lincoln ignores both our history and the flexibility of our institutions. To understand why there is a group of folks who blame Lincoln rather than Washington, Jefferson, Jackson, Polk, the two Roosevelts, Wilson and so many others, we must remember that Lincoln was the one who deprived slaveholders of their slaves, the most valuable asset class in the world at that time.
It was all about slavery then and it is all about slavery now.
It wasn’t all about slavery then or now. That is just a post-hoc rationalization peddled after the war. It was certainly partly about slavery.
Given that the War did happen, it was a tragedy that Lincoln didn’t survive. He would have been far better post-War than the Radical Republicans who followed.