In The Phantom Tollbooth, everyone in the Lands Beyond suffers from the loss of Rhyme and Reason. These two princesses, while real characters, could also be seen as symbols of what their names represent. Everyone in the Lands Beyond maintains his own unique philosophical viewpoint, and it seems like the more these folks stubbornly stick to their guns, the less wise they become. Their views of the world suffer without the balance of Rhyme and Reason to make them think practically about the way they live their lives. Nevertheless, as Milo travels through these troubled lands, and encounters all these different philosophies, his mind expands with the addition of these new perspectives. Now the trick is to take all this new knowledge and apply it to his own life.
The character with the most well-rounded point of view in The Phantom Tollbooth is Milo, because he is sympathetic to all the other characters' points of view and even temporarily adopts some of them.
When King Azaz and the Mathemagician cast out Rhyme and Reason, they revealed themselves to be as foolish as the demons that populate the land of Ignorance.