What abstract qualities are portrayed by the evil young men in "The Pardoner's Tale"?

In Chaucer's "The Pardoner's Tale," the Pardoner, who is a very corrupt clergyman who is only interested in becoming rich from the donations of his parishioners, tells a story that is meant to warn against greed. He tries to illustrate to the members of his church (and in the context of The Canterbury Tales, to his fellow pilgrims) that greed is the root of all evil. 

The three young men in the tale drunkenly...

In Chaucer's "The Pardoner's Tale," the Pardoner, who is a very corrupt clergyman who is only interested in becoming rich from the donations of his parishioners, tells a story that is meant to warn against greed. He tries to illustrate to the members of his church (and in the context of The Canterbury Tales, to his fellow pilgrims) that greed is the root of all evil. 

The three young men in the tale drunkenly pledge to kill "Death" at the beginning of the story (a personified version of the Plague) and swear brotherhood to each other; they promise to be loyal and to protect one another. However, on their quest to find "Death," they come across a very old man who points them to a tree where he says they can find death. What they find there is a large quantity of gold. It isn't long before each of the young men starts plotting ways to get more of the gold for himself. None of the men is satisfied with just his third of the gold. Two of the men send the youngest man into town for supplies (since they need to guard the gold at the tree until nightfall to avoid suspicion), and as soon as he leaves, they begin plotting his death so that they can split the treasure two ways instead of three. While he is in town getting food and drink, the youngest buys poison to put into the other two men's drinks so that he can have the gold all to himself. They all end up killing each other. No one gets the gold, but the old man was correct: they did find "Death" under the tree.

The moral of the story is that greed leads people to commit evil acts. Abstract qualities like selfishness and betrayal are also exemplified in the behavior of the young men. Ironically, the Pardoner is also greedy and only tells this tale to make the parishioners feel guilty and obligated to donate their money so that they are not corrupted by excessive wealth.