Swift's real reason for writing "A Modest Proposal" was to shame the wealthy people of Ireland and England who were responsible for the sufferings of the poor of Ireland. However, he chose to pretend that he was totally disingenuous in suggesting that the wealthy readers should consider eating the Irish children if their parents could not afford to support them. He even suggests that
. . . a young healthy child well nursed, is, at a year old, a most delicious nourishing and wholesome food, whether stewed, roasted, baked, or boiled, and I make no doubt that it will equally serve in a fricasie, or a ragoust.
Since he could not state his real reason for writing the essay, he felt the need to offer some fictitious motive which would be in keeping with its satirical spirit. He had been pretending to be just as heartless as his readers, and therefore he decided to conclude the essay by suggesting that he would be willing to sell his own children to be eaten by affluent Irish and English cannibals but unfortunately
I have no children, by which I can propose to get a single penny; the youngest being nine years old, and my wife past child-bearing.
In other words, he can't be accused of having an ulterior motive in making the horrible suggestions he has been making. Furthermore, the ambiguous nature of the concluding paragraph leaves the reader wondering whether he should take this man seriously, whether he is insane, or whether he is being facetious. If the author of "A Modest Proposal" is trying to be funny, it doesn't make him seem any the less sadistic in the reader's eyes, since he has chosen such an inappropriate subject for mirth. It must have been Swift's intention to leave readers guessing--and readers have been guessing about it ever since he first published it in 1729. He wanted his readers to give the proposal serious consideration. He calls his essay
A MODEST PROPOSAL for preventing the children of poor people in Ireland, from being a burden on their parents or country, and for making them beneficial to the publick.
If his proposal is unthinkable--then what is a better proposal for preventing the poor people of Ireland, from being a burden on their parents or country, and for making them beneficial to the publick?
Throughout his essay Swift is trying his best to be outrageous and yet to seem perfectly sincere and, as he says, modest. In his final paragraph, he concludes in the same spirit in which he has presented his proposal and his arguments in its support:
I profess, in the sincerity of my heart, that I have not the least personal interest in endeavouring to promote this necessary work, having no other motive than the publick good of my country, by advancing our trade, providing for infants, relieving the poor, and giving some pleasure to the rich.
He could not, figuratively speaking, crack a smile at any point to suggest, "Hey! I'm only joking." He writes in a consistently somber, serious, logical, rational tone and supports his ideas with facts and figures. That explains why his final paragraph remains in the same tone and spirit as all the rest of his essay. It is the tone and style of this unusual work that have won it a permanent place in English literature. Swift shows his great genius in choosing such an original and attention-getting form in which to present a picture of the sufferings of the poor oppressed people of Ireland.