"The Knight's Tale" shows what happens when the rules of two different systems – chivalry and courtly love – come into conflict with one another. Palamon and Arcite have sworn a knightly oath to be loyal to one another, but they both fall in love with the same girl. The problem is, the rule of chivalry, which demands knights keep their oaths, is tested by the rule of courtly love, which demands that a knight put his love for his lady before everything else. This inevitably leads to a big, fat fight between the two knights. The tale solves the problem in the character of Duke Theseus, who proposes an organized contest to solve the feud. The winner gets Emily.
Theseus is the order-bringer and rule-protector from the very beginning of "The Knight's Tale," when he sets its plot in motion by punishing a king who has broken the societal rule that bodies must receive a proper burial. Yet his desire for an orderly universe is tested when Arcite, the knight who wins the joust and Emily, dies in a freak accident immediately following the battle. To disprove the seeming randomness of this event, Theseus lays out a vision of an orderly universe with all creation deriving its existence from God. In this universe, death is a part of God's plan for creation, a sign that all is as it should be, so rules and order still prevail.
Arcite's seemingly random death presents the ultimate challenge to Theseus's desire for an orderly world.
"The Knight's Tale" portrays love as the law that trumps all other laws.
"The Knight's Tale" shows how even love must yield to laws that are more powerful than it.