Chaucer's "The Pardoner's Tale" is particularly ironic.
Irony, as Dr. L. Kip Wheeler puts it, is:
...saying one thing and meaning another.
A great deal of the information in Chaucer's Prologue to the Canterbury Tales is garnered by reading between the lines, as Chaucer describes his larger-than-life characters with a "twinkle in his eye," and tongue in cheek. A student of human nature, Chaucer saw beyond appearance to the heart of the individual. And although the structure of his tale is based upon a pilgrimage to the Canterbury Cathedral, where Thomas à Becket was martyred by King Henry II's men-at-arms, many of those who Chaucer "travels with" are anything but holy in behavior or mindset. However, Chaucer allows the audience to judge his characters while he, acting like a member of the pilgrimage, reports what he sees.
The Pardoner's job is to "sell" indulgences ("forgiveness") to those who have sinned. (Chaucer was a critic of this and other aspects of the Church of his time.) The Pardoner is supposed to be a member of the "clergy." This means he was employed to serve the public in a religious way, which would have entailed giving up his worldly possessions, putting others before himself, dressing in plain clothing without adornment, and devoting his life to the good of others.
Ironically, the Pardoner is stylishly-presented, concerned with his good looks, carries "hot" (or stolen) pardons from Rome, and has fake "souvenirs," such as a pillowcase he presents as the veil of the Virgin Mary, as well as fragments of the sail of St. Peter, used to impress unsophisticated country "clergymen."
The last part of this ironic portrait of a man of the cloth who is more interested in benefitting himself than the congregation he serves, is the pardoner's songs offered up as if in praise of God, while in truth, the better he sings (he knows), the more money will be in the offering plate he passes around—for him. That which seems to indicate what a dedicated man of God he is, shows more how dedicated he is to filling his own pockets.
Irony is developed in numerous ways at the end of the tale. The three "rioters" who set out from the tavern to kill Death itself eventually manage to kill each other--the primary irony.
Also, two additional ironies can be identified in the conclusion of the tale. Two of the three stab the third, but they themselves die after drinking the poisoned wine that had been brought back to them by the man they had just killed. Ironically, they had been killed by a dead man.
The irony that drives the plot of the tale lies in their finding the gold florins piled on the ground:
No longer was it Death those fellows sought,
For they were all so thrilled to see the sight,
The florins were so beautiful and bright,
That down they sat beside the precious pile.
It is ironic that when they gave up their search for Death, they set upon the path that would take them directly to it; it was their greed that led to their deaths.
The irony in "The Pardoner's Tale" is largely due to he fact that Chaucer has been put this extremely powerful and moralistic tale in the mouth of the corrupt, vain and lascivious Pardoner. One thing is certain. Despite his numerous flaws, the Pardoner is a master storyteller and he has the pilgrims hanging on his every word. He has told a tale that demonstrates the consequences of greed and deception, yet the Pardoner is a blatant example of these vices. He has readily boosted of his fake holy relics (pig bones and pillow cases) and brags about his own self-indulgent life. Of course, one may wonder why the Pardoner reveals the truth about himself in the same manner that travelers often do, believing that they will never see their fellow travelers again. Indeed, the Pardoner is so proud of his ability to deceive others, that he cannot resist attempting to sell his fraudulent goods at the conclusion of his tale.