What was the dispute over the southern slave population?

During the Constitution, the South wanted the slaves to count as part of the population because the more the population, the more the representation a state had. The North argued that this was unfair and the the South were taking advantage of their slaves, because they didn't treat the slaves like people. In the end, they reached what is known today as the Three Fifths Compromise, meaning that a slave would count as three fifths of a person.