Swift, by 1729, was quite late in his career, being already over 60 years old. If his more careful, complex, difficult satires had not been sufficiently understood and appreciated, it was time to bang the people over the head with a satire that they could recognize and which would renew interest in his other works. Although Gulliver’s Travels was fresh in people’s minds, it was already 25 years after A Tale of a Tub . Anyone who becomes intrigued by Jonathan Swift after reading “A Modest Proposal” should go on to the works that are worthy of a more sophisticated critic.
Scatology has a long literary association with satire,    as it is a classical mode of the grotesque , the grotesque body and the satiric grotesque.   Shit plays a fundamental role in satire because it symbolizes death , the turd being "the ultimate dead object".   The satirical comparison of individuals or institutions with human excrement , exposes their "inherent inertness, corruption and dead-likeness".    The ritual clowns of clown societies , like among the Pueblo Indians , have ceremonies with filth-eating .   In other cultures, sin-eating is an apotropaic rite in which the sin-eater (also called filth-eater),   by ingesting the food provided, takes "upon himself the sins of the departed".  Satire about death overlaps with black humor and gallows humor .
Satire is not the same thing as irony. Satire uses irony, sarcasm, and other literary devices to make a point. In general, a satirical piece speaks of something ridiculous in a serious manner in order to make a point to society. The best example I can think of is A Modest Proposal by Johnathan Swift. In this piece, he proposes that rich people eat the babies of the poor in order to help control the population and support the less fortunate. Clearly, he isn't being serious. He is pointing out a problem by proposing a ridiculous solution that most people will find offensive enough to pay attention to. Irony is a "situation in which there is a sharp incongruity or discordance that goes beyond the simple and evident intention of words or actions." In the novel The Crucible, I think there is generally more irony than satire. Perhaps we can see some example of satire in the reactions of the townspeople and the injustice in the trial process. Still, this work contains more example of irony, particularlly dramatic irony.