Was in a conversation with someone who argued that slaves don't produce surplus value, that surplus value is unique to a worker-owner relation as in liberalism. Is anyone familiar with this idea? It didn't make a great deal of sense to me. One would think that slaves would give you as much if not more surplus value than workers you have to pay.
Surplus value = the value generated - cost of labor power
Slaves do create much more surplus value than workers. Remember that earlier supporters of classical liberalism were slave owners or supported the slave trade