Irony of Gratitude
Kit begins the novel unaccustomed to hard, tedious work. She is expected to help with household and farm chores, one of which is the carding of wool so that it can be spun into thread or yarn later. This is a long, repetitive task which never seems to end, and Kit believes they are making no progress. Mercy, who is crippled, is sincerely grateful for the help and says that the work is going much faster than usual.
Irony of Insight
The residents of Wethersfield believe they are more enlightened and wise because of their religious beliefs and their piety; however, their isolation has made them backward in many respects: they have developed unreasonable superstitions. The same sense of community, unity, and righteousness that developed from their shared religious fervor leads them to develop a mob mentality toward the outsider Hannah and also to Kit, whose behavior does not conform with their narrow beliefs as to what is or is not right.
Irony of Outcasts
By shunning Hannah, Nat, and Kit, the villagers accidentally encourage them to become friends and to help one another in times of danger. Shunning and expulsion, intended to weaken them, actually strengthened them all and helped them to rescue them from attack by the badly misguided people of Wethersfield.
Irony of Fear
The townspeople are very afraid of "witchcraft"-- the practice of evil, destructive magic in collusion with the Devil. Despite the ridiculousness of the idea, they persist in finding "evidence" of evil spells being cast because they have already made up their mind to believe that they are in danger. Their fear is completely baseless, and in fact it makes the villagers into dangerous, antagonistic people when they decide to preemptively attack two innocent women.
Irony of Helping
The things Kit does to help others, such as jumping into a pond to save a child's doll or teaching a child mistakenly identified as a "halfwit" to read by copying the child's own name into a book, are later used against her by the people charghing her with witchcraft. The more Kit tries to help others in Wethersfield, the more they turn against her.
Irony of Privilege
Kit's deceased grandfather was a very wealthy man in Barbados, so when Kit was growing up she had lots of servants who from a historical perspective were very likely to have been slaves. Slavery was not abolished on the island of Barbados until 1834, and this novel was set in 1687. When Kit arrives in Connecticut and meets her aunt and uncle, she is immediately put to work, and it is not until she herself is forced to card wool, sew, or prepare food that she realizes how difficult the work is or how incompetent she is at it. She does not appreciate the privileged environment in which she was raised until it is gone forever.
