Explain the proslavery and abolitionist arguments of the Antebellum period.

Proslavery arguments in the South were economic, religious, historical, and social. Southern whites argued that their economy would collapse without slave labor. This was the "necessary evil" argument. They reasoned that nobody would harvest the cotton, sugar, and tobacco if slavery were abolished. The crops would rot and the United States as a whole would suffer. The agrarian economy of the South benefitted the entire country, not just Southern plantation owners, and helped to make the United States a powerful country. Since the Southern economy could only run effectively with low-cost slave labor, some argued, slavery was here to stay.
Proslavery proponents also turned to the Bible's seeming endorsement of slavery in such verses as "slaves, obey your masters." If the Bible approved of it, this argument went, it must be an acceptable institution. Further, the historical argument contended that slavery had built great civilizations in the past, such as ancient Greece and Rome, and therefore was a natural and a beneficial institution. One advocate of this position was William Harper, who wrote a book explaining these ideas called Memoir on Slavery. Finally, especially in the later part of the Antebellum period, slaveowners started to argue aggressively that slavery was not just a necessary evil but a positive social good. It civilized the inferior Africans. Slaves were well treated on happy plantations and received security. According to this argument, they had better lives than factory workers in the Northern states.
Abolitionists argued that slavery was a social and moral evil that harmed not only the slaves but their owners and society as a whole. Slaves were brutalized and lived in fear and forced ignorance, while whites became corrupted by too much power and also lived in fear. Their fear was of the slaves rising up and murdering them, which abolitionists argued was the only logical outcome of such an unjust system. White children were corrupted into cruelty by having helpless slaves at their beck and call.
Abolitionists argued that slavery was anti-Christian, because God had made humans in his image and that image was one of dignity and freedom. They argued that the New Testament said that people should live in love and that slavery was an inherently unloving institution based on controlling other people against their will.
Abolitionists also argued that slavery violated the very principle of "all men are created equal" that was foundational to the United States. The United States betrayed what it stood for in allowing slavery.
The abolitionists also contended that the South had viable economic alternatives to slavery. For example, the Quaker Ellicott brothers came to Maryland, a slave state, and gave land and help to farmers who agreed to grow wheat, which did not require slave labor.
Primarily, abolitionists relied on arguments that showed the real, living evils of slavery. Abolitionists like Frederick Douglass, a former slave, told the slaves' story from the slaves' point of view, showing the cruelty, abuse, and sadism built into the system. In Uncle Tom's Cabin, Harriet Beecher Stowe depicted the lives of slaves, based on her own observations while visiting relatives in slave-owning states, to show that the life of a slave was uncertain and that the slaves were at the mercy of a cruel system. Whatever plantation owners claimed about the "happy plantation" benefitting the slaves, the abolitionists could show that this idea was quite simply a myth. The abolitionists challenged the white slave owners to sell their own children into slavery if it was such a good and beneficial system for the slaves. Tellingly, the slave owners did not take the abolitionists up on this offer.