Also, hot take and all ... but until a sizable portion of those who participated in the parties - White American men - started to see Black people as literally biologically equal, let alone equal in ability or potential or moral worth or whatever, classifying slavery as an overly ideological issue is somewhat troubling to me. In 100 years, if Americans all of a sudden make a big deal that our actions are leading to an increase in starving Sub-Saharan African children or something, it's going to be somewhat misguided to start looking back at politicians of our age and deciding who was "liberal" or "conservative" based on that issue, EVEN IF it's agreed that there is a clear liberal and conservative position to take on it, and deciding too much about their ideologies based on that stance or lack thereof. It might be Mitch McConnell's pet issue because he literally knows one Sub-Saharan African lady, while Chuck Schumer doesn't like to bring that issue up for political reasons ... doesn't change their ideologies on other stuff.
These people certainly understood slavery in ideological terms:
Mr. President, if we recognize no law as obligatory, and no government as legitimate, which authorizes involuntary servitude, we shall be forced to consign the world to anarchy; for no government has yet existed, which did not recognize and enforce involuntary servitude for other causes than crime. To destroy that, we must destroy all inequality in property; for as long as these differences exist, there will be an involuntary servitude of man to man.
Your socialist is the true abolitionist, and he only fully understands his mission.
In fact, the European Socialists, who, in wild radicalism ... are the correspondents of the American abolitionists, maintain the same doctrine as to all property, that the abolitionists, do as to slave property. He who has property, they argue, is the robber of him who has not.
“La propriete, c’est le vol,” is the famous theme of the Socialist, Proudhon. And the same precise theories of attack at the North on the slave property of the South would, if carried out to their legitimate and necessary logical consequences, and will, if successful in this, their first state of action, superinduce attacks on all property, North and South.
We warn the North, that every one of the leading Abolitionists is agitating the negro slavery question merely as a means to attain ulterior ends, and those ends nearer home ... They know that men once fairly committed to negro slavery agitation - once committed to the sweeping principle, “that man being a moral agent, accountable to God for his actions, should not have those actions controlled and directed by the will of another,” are, in effect, committed to Socialism and Communism, to the most ultra doctrines of Garrison, Goodell, Smith and Andrews - to no private property, no church, no law, no government - to free love, free lands, free women, and free churches.
I shall in effect say, in the course of my argument, that every theoretical Abolitionist at the North is a Socialist or Communist, and proposes or approves of radical changes in the organization of society.
The same logic and sympathy - the same conviction and ardor - which made us an Abolitionist twenty years ago, make us a Communist now.