Prynne, who apparently resembles a saintly figure as she stands on the ignominious scaffold, seems unjustly humiliated, especially with the ironic comparison.

It is ironic that some "leading inhabitants" of the town have been discussing removing Pearl from her mother's care. Some argue that Pearl is of "demon origin" and so they feel that separating her from Hester would actually be better for Hester's soul; the child might present a "stumbling-block" to Hester's salvation. On the other hand, Hester has committed a grave sin and might corrupt the child's soul, if she is not corrupted already. The reason this is ironic is that Hester feels as though her responsibility to Pearl is what keeps her on the right side of the law and of God. At the end of the next chapter, for example, Governor Bellingham's sister, Mistress Hibbins, invites Hester to a witches' meeting with the Devil in the woods outside the town that night. However, Hester tells her that she must "keep watch over [her] little Pearl." She admits,

Had they taken her from me, I would willingly have gone with thee into the forest, and signed my name in the Black Man's book too, and that with mine own blood!

Pearl's presence in her life actually saves Hester from further, greater, sin, and, without Pearl, Hester would be willing to sin a great deal more. Therefore, it is ironic that town leaders would want to take Pearl away in order to help Hester when it would actually hurt her; it shows how little they truly understand.

Chapter 9, which is properly titled "The Leech" describes Roger Chillingworth as just that: some animal force that has opted to attach itself to Arthur Dimmesdale in order to extract whatever life is left in the man, as this is the only way that he would get to find out what is the ailment of the soul that is driving the reverend crazy. Granted, leech was also a colonial name given to doctors (as one of their premiere methods for curing people was bloodletting through leeches). 

By saying that Chillingworth was "scrutinizing" his patient, Hawthorne uses a play on words. First, Chillingworth scrutinizes the way that a doctor would, but he really is not a physician. He is a scholar who knows more than the average individual about many things, including the medical sciences. He infiltrates into the village and is accepted immediately at face value, which says a lot about the villagers' critical thinking skills. It is true, however, that later on he finally is seen for the impostor that he may be, and he loses the trust of the people since he starts to appear suspicious to them.

The second irony is that, at this point, Chillingworth's scrutiny is not of the medical kind, but of the personal kind. He is adamant in knowing what is eating away at Arthur. He makes more questions about the nature of Arthur's soul than at the state of his body, which is what he really should be asking Dimmesdale about. Chillingworth goes as far as telling Dimmesdale that there is a doctor of the soul to which he should confess his issues, which Dimmesdale completely refuses to do.

"Many, many a poor soul hath given its confidence to me And ever, after such an outpouring, Oh, what a relief have I witnessed in those sinful brethren, even as in one who at last draws free air, after long stifling with his own polluted breath.

It is all a cheap attempt to get questions answered that Arthur is just not ready to give up yet. 

Therefore, the irony lies at the heart of what Chillingworth aims to do, which is to make Arthur confess. To do this, Roger poses as a friend and support system to the poor Reverend, grilling him with questions in the process and, perhaps, making the man more ill than what he was before. 

Hawthorne portrays the Puritans as thinking they had a perfect society. However, as he points out in the first chapter, one of the first things they needed to built in their so-called utopia is a prison for people who broke their laws. During the course of the novel, the society also includes a witch who just happens to be the sister of the governor, an adulteress, a minister who is an adulterer, a town doctor bent on revenge and a child borne out of wedlock. Thus, one of the developing themes is that no person is capable of perfection and therefore we should "be true, be true" and show our real selves to society, not hide behind a religious facade that is not realistic for anyone to achieve.

One of the most apparent levels of irony lies in the notion of social condemnation.  The social order in which Hawthorne writes is one where individuals feel comfortable in declaring others as "immoral" when they act and behave in manners that are worse than those that are accused.  Hester wears "the scarlet letter" and endures public criticism even though she is far from morally impure.  The fact that she makes peace with her condition, staying in the town and in America, as opposed to fleeing it, might indicate that she has moral strength than those who are accusing her.  Additionally, it can be suggested that it is ironic that Hester is probably more courageous on a moral and spiritual level than Dimmesdale, a man "committed" to the cloth.  The irony is that he lives in silence and internal shame with public praise, while Hester takes the brunt of social criticism, even though she is more morally upstanding.  I think one could suggest that this operates on a level of irony.

On the face of it, Arthur Dimmesdale is the epitome of holiness. A devout man and a Puritan minister who is widely admired and respected in the community, he is also an adulterer who has conducted an illicit relationship with a married woman, Hester Prynne. As a result of this affair, Hester became pregnant.

At that time and in that place, both adultery and the begetting of illegitimate offspring were both considered deeply sinful and wholly deserving of punishment and public opprobrium. One can see, then, the irony of a Puritan minister of all people committing such a serious sin.

Still more irony can be observed when Dimmesdale preaches sermons about sin the townspeople. Far from diminishing his effectiveness as a preacher of God's word, Dimmesdale's sin allows him to be more effective in reaching his congregation. This is because he has a personal experience with sin that makes him something of an expert on the subject.

The members of Dimmesdale's congregation are powerfully moved by his sermons, believing him to be a miracle of holiness. Yet, in an ironic twist, it is only because Dimmesdale has committed a very serious sin that he's able to move his listeners in such a powerful way.

In The Scarlet Letter, the Puritan colony that has been intended to be, as John Winthrop said in 1630, "a city upon a hill" setting an example of moral behavior for others, is instead a Massachusetts colony that has as its first building a prison, whose rusted and ponderous door clearly indicates that everyone in the colony does not live the exemplary life expected. 

However, this exemplary life is one that is fraught with denial, denial of the human passion that dwells in the human heart. Somehow though, a symbol of this forbidden passion, a rose bush, ironically grows "out of the stern old wilderness" outside the prison door, perhaps out of the dirt from the "footsteps of the sainted Ann Hutchinson,"  Hawthorne writes.  A Puritan independent who led Bible discussions for women that later appealed to some men, Hutchinson was later tried and banished from the Massachusetts Bay Colony for being a dissident.  Ironically also, her implicit rejection of state authority to prescribe religious interpretations was later incorporated into the American Constitution.

In another sharp irony, Hawthorne describes the Puritan Hester as beautifully resembling a Papist (the foes of the Puritans) depiction of the Madonna with Child, an almost sacrilegious depiction since Hester has had a child out of wedlock.  Then, too, the Reverend Dimmesdale, a Puritan minister who should be unmoved by the scandalous sin, seems emotionally moved by the appearance of Hester and child upon the scaffold as he stands holding his heart.