ZMag.org explains a bit about what Ron Paul stands for, but I want to address something that doesn't usually get covered. Paul thinks the Civil War, which resulted in the legal end of slavery in the United States, was wrong and should never have been fought. Why? Because he thinks it hurt property rights. His asinine alternative to fighting the American Civil War doesn't make sense, either.
Let's analyze Ron Paul's nonsense. He is against the federal government intervening in any capacity to do anything for the common good. He preaches that the free market will take care of all ills (yeah, the Great Depression was just a shining example of this, right Ronnie-boy?). In Ron Paul's twisted imagination, the federal government cannot do anything other than fund the military. That's it. And his 'privatize everything' position makes even that highly unlikely.
But let's get back to the subject of "buying the slaves". With what money? Ron Paul doesn't believe in charging taxes under any circumstances, so where would he have gotten the money to purchase the slaves? From the free market? Doubtful, since the free market dictates that it do only what is in the interests of the market. And it certainly was not in the interests of the free market in 1860 to end slavery, since slavery was a key component in its function. Free labor, and you don't even have to worry about safety regulations or all of that "socialist" claptrap about unalienable human rights. Because slaves were not considered human, they were considered property.
Which brings us to the next problem in Ron Paul's answer. Property rights. The boy is your typical property rights zealot, unwilling to do or allow anything that he thinks would harm property rights. And slaves, as we know from history, were considered property. Suppose the South had refused the sale of its slaves? What then? Ron Paul would have thrown up his hands, given up trying to free the slaves, and put off the problem for future generations to handle.
The sad reality of Ron Paul's anti-Lincoln rhetoric is that it hides the racism of a boy whose hatred for government precludes him from doing anything that might achieve some good for the public, because it would interfere with his precious free market. Had Ron Paul been president in the 1860s, we'd still have slavery today. Or the Civil War would have been fought decades later, but still fought, and probably with even greater loss of life.