According to my view slavery was not a good practice at all.
Some reasons to support that are-
1)slaves were treated very badly as if they were not even humans and did not have any rights. According to the constitutional rules everyone should be treated equally
2) Slaves could have been of any age 5 years kid or a 80year old man they were tortured badly.
3) many slaves died starving or due to diseases but no one cared about them.
4) what was someone's fault if he was black in colour? he didn't want it he got it.