Why Do We Think Slavery is Evil?

[KevinM1]

I don't believe that anyone can really make a strong case as to why slavery in on its own is evil. You can make the emotional arguments. Like Matt D on the atheist experience will always ask, Do you want to be a slave? And of course no one in this day and age would say yes. But you can't really make a logical reasoned argument for why it is wrong or immoral without appealing to emotions. Its easy to say that its wrong to make another human your property but why isn't it the same as a sports league? I know that this will get quickly shot down because of reasons like the fact that Kobe Bryant can walk away from basketball at any moment and he is free to roam about as he wants. But we have to remember that until just a couple hundred years ago, humans in general worked 10-12 hours a day doing laborious jobs. Its not like they even had the free time to go anywhere, or even the ability to go more than a couple miles.

  But the problem is that we always think back to slavery in the south or have an imagined view of slavery where they're all chained up at night time. I don't know if thats how slavery in the bible worked. I believe that they did have certain freedoms but free or not you would be stuck doing labor 6 days a week. I know this isn't a popular view but I am curious if anyone has thoughts on slavery that don't appeal to emotions

Why can't morality appeal to emotions?  Would starting an argument based on consent be appealing to emotions in your opinion?