Dear Dr. Boli: My nephew was asking me why slavery was objectively bad, and I couldn’t think of an articulate reason off the top of my head. So I smacked him. But why is slavery objectively bad? —Sincerely, Jefferson Davis (no relation).
Dr. Boli: Slavery is evil because it is not right for one human being to have godlike power over another. In the wise and mysterious plan of creation, such power is meant to be wielded only by major corporations. If slavery were allowed, it would interfere with the corporate world’s ability to reduce us all to a state of abject and profitable peonage: it would deprive a whole class of persons of the ability to purchase manufactured consumer goods and electronic services that come with binding non-negotiable “agreements” to which we agree simply by using the goods or services.
Dr. Boli is sorry to disappoint you if you thought there was a moral argument against slavery. Perhaps there is, but it has not been found relevant.