Chattel slavery is morally wrong, objectively. But the way a lot of individuals have accepted as ‘normal’ or ‘moral’ happens to be the way people in some societies at some times have defined as slavery.
People speak of being, “A slave to my wife’s wants”, “a slave to the time clock”, doing slave labor, ‘slaving away’, etc.
In economic systems where exchange of labor was required as opposed to exchange of goods, for an individual to ‘sell himself into slavery’ (usually to feed a family) might have been a workable system that was seen as moral for the time, but either is no longer a viable system or people have grown to see the possibilities for system abuse and the personal degradation of making a ‘person’ into a ‘thing’.
The morality of ‘owning a person, body and soul’ is objectively morally wrong’; only God is our Maker and ‘Owner’. But people did not always realize this clearly, precisely because the way people see slavery has not always been clear-cut.
Torture, also, is morally wrong objectively. The fact that people’s understanding of what torture ‘accomplishes’ and that some looked to ‘the end justifies the means’, or felt that there were ‘degrees’ where something stopped short of unacceptable pain (remember, people still do not understand the way pain works in an individual, and why some people can withstand much higher degrees of pain than others) means again that people’s understanding develops, and that also people tend to try to justify things which make them uncomfortable when they are recognizing that something is wrong, but feel that there is somehow a necessity to do it anyway.
It all comes from people being human; from them never getting things ‘perfectly right’, and from, one way or another, individuals making mistakes. The fact that people made mistakes for years, or make mistakes now, in being able to see where things are objectively wrong, doesn’t make the things just ‘relatively’ wrong or right because the PEOPLE don’t ‘follow the rules’.
