Help?

Friends, lj-users, lend me thine ears. (or eyes.) Do any of you know any books that touch on discourses surrounding slavery during the early 18th century (as in, around the time ye Robinson Crusoe was published?)Most stuff I find is pre-Victorian, or around Equiano's era. And that's great, but I need stuff that said how people (other than Danny-boy Defoe) thought about it at the time, how they justified it, if any had any moral compunctions about it, etc, etc.