Having the three fifths compromise was a good idea when it was introduced in 1787 because it targeted slavery. Slavery was a big issue early in the American history. Freedom was an important issue to the people who had founded the country but still slavery was legal. Everybody was against slavery but it was important to southern United States, and to abolish it could easily make the nation fall apart before it had a chance to grow.
Many did not consider slaves to be a citizens some southerners wanted the congressional representation so it would allow slaves to be counted as citizens. There for the Three-Fifths Compromise was introduced for the North and South. During this time it was essential that the economy would remain strong or else things could start to fall apart. Which would then cause the country to lose everything that it has already gained.
If the north manage to get slavery abolished it could of very well lead to the failure of the United States. The country at the time depended on the economy growth of the South so at the time slavery was considered less of an issue. Southerners at the convention insisted that their slaves be counted when allocating representation in Congress, even though everyone understood that slaves were considered property and had no political rights. Throughout the convention the slave owners also made it clear that they did not expect an end to slavery in their state.
The debate was all about political power many of the northerners objected to the idea of counting slaves for the representation for the nation. All the Southerners insisted that the allocation of representation in Congress had to take slaves into consideration. Most Northern delegates acquiesced on this point because they were afraid that otherwise, the Southern states would not support the new Constitution. By partially counting slaves for representation, the South gained a huge bonus in the House of Representatives even though these states considered their slaves to be property they had no political voice and no legal rights.
The value to the South of the three-fifths clause became clear in the seven decades after the Constitution was written. Southerners were able to block federal legislation hostile to slavery and get the House to pass numerous laws that protected slavery.