Cotton's assertion that slavery was "a necessary evil" is very similar to the defense Stalinists made of their repressive(and repressively ANTI-socialist, since Stalin spent more time suppressing support for the idea that working people should ACTUALLY control the means of production than he did repressing anyone or anything remotely "conservative") methods: "you have to break some eggs to make an omelet".

There was any part of this country that nad no alternative to slave labor as a basis of its economy. If they could harvest corn without slavery in Iowa, they could harvest cotton without it in Alabama. if they could build buildings that were strong enough to last for centuries in large cities in the Northeast without keeping the construction crews in chains and selling off their kids to other building contractors, they could have done the same with the White House.

There was simply no excuse for slavery, wherever it happened or happens. And the fact that it still happens in other places now does not let those who once owned slaves here off the hook.