Final answer:
Guy de Maupassant uses irony in "The Piece of String" to emphasize the destructive power of false accusations and the stubbornness of prejudiced opinions through the protagonist's tragic situation.
Step-by-step explanation:
Guy de Maupassant uses irony in "The Piece of String" to highlight the tragic and sometimes unfair nature of society's judgment. The protagonist, Maitre Hauchecome, is accused of theft after picking up a piece of string off the ground, which he claims was mistaken for a lost wallet. Throughout the story, Maupassant uses situational irony to underscore the protagonist's innocence and the town's persistent belief in his guilt, even after the real wallet is found and returned. This contrasting between appearance and reality, alongside Hauchecome's desperate but futile attempts to clear his name, serves to emphasize the theme of the destructive power of false accusations and the stubbornness of prejudiced opinions.