What are the pros and cons of slavery?

Pros:

They render free trade; slavery provides free labor to European farms where they get high returns on the farm produce, thus improving the economy.

cons:  It's inhumane; those who buy and sell slaves are violating human rights. People should not be treated as commodities in colonies where they are exploited cruelly.

Explanation:

i would say that the politicial parties from state to state varies.