How do irony and a serious tone make A Modest Proposal a satire?

A Modest Proposal (1729) is a masterpiece of satire that utilizes a calculated blend of rational deliberation and horrific conclusions to critique the legal and economic exploitation of Ireland by the English government.12

The essay functions as a satire through the following techniques:

• Serious Tone: Swift adopts the persona of a public-spirited, rational citizen presenting an economic treatise. By maintaining a grave, practical, and objective tone, he mimics the style of contemporary political pamphlets, which forces the reader to confront the absurdity of the proposal against the backdrop of its "logical" presentation.123
• Sustained Irony: The core of the satire lies in the gap between the narrator’s calm, "modest" delivery and the monstrous nature of the suggestion—that the children of the Irish poor be sold as food to wealthy landlords. This irony exposes the dehumanizing effects of English policies, effectively highlighting the dire economic conditions and the callousness of those in power.243

By combining these elements, Swift forces readers to look past the surface-level argument to recognize a savage indictment of systemic injustice.12