Question

How did pro-slavery advocates justify slavery?

Answer 1

See below

Explanation:

" Before 1830 - The South defended slavery as a necessary evil. They argued that the emergence of cotton as the most important cash crop in the country made slaves necessary.

After 1830 - A number of factors (outlined below) forced southerners to change their defense. Instead of defending slavery as a necessary evil, they began to defend slavery as a "positive good." They argued that the slaves were in actuality happy, content and well cared for. They even went as far as saying that being a slave was better than being a worker in a northern factory, a condition referred to as "wage slavery."

Source and more details:http://www.socialstudieshelp.com/lesson_30_notes.htm

Some also blamed capitalism to be more violent and unfair that their system, they used paternalistic rhetoric.