Imagine two brothers have been dropped together into the middle of a forest, each with the same map and the shared goal of getting home. Each has a compass to help him navigate, but each compass points in a different direction for north. Both young men are sincere in their attempts to get home, but in this situation it will be nearly impossible for them to agree on the best route. This disagreement will exist not because of a lack of intelligence or differing goals, but rather because of a fundamental difference in their guiding force—compasses that disagree on which direction is north.