The purpose behind trading off on subjection was the Northern states needed higher duties thus as a greater segment of the nation were given this, however, the Southern states additionally requested something. So the Framers keeping in mind the end goal to give the littler states more portrayal in the House was permitted to consider each slave a large portion of a man.
I agree that the trade-off disregarded crucial principals since you can't consider somebody just a large portion of a man and the Framers ought to have attempted to think of an approach to abrogate subjection.