In A Modest Proposal, Swift doesn't reveal his plan until later in the essay. What is the effect of this delay?
It is hard to avoid the conclusion that this essay has been very carefuly scripted and drafted precisely to delay the "unveiling" of this very immodest "modest proposal." It is important therefore to ask what Swift does in the lead up to the revelation of his plan. Swift is very careful to try and establish the voice and tone of the essay to present himself as a caring, concerned and earnest individual who sincerely wants to help alleviate the poverty and terrible famine in Ireland. The reference to numbers and statistics likewise presents his voice as credible. Note an example of how this works in practice:
I think it is agreed by all parties, that this prodigious number of children, in the arms, or on the backs, or at the heels of their mothers, and frequently of their fathers, is in the present deplorable state of the kingdom, a very great additional grievance; and therefore whoever could find out a fair, cheap, and easy method of making these children sound and useful members of the commonwealth would deserve so well of the public, as to have his statue set up for a preserver of the nation.
Note how Swift is trying to show his reasonable nature by appealing to "all parties" and identifying areas of commonality between them all. Having established himself as a reasonable and even caring speaker, who is concerned for the plight of the poor, the shock of reading his exact proposal is that much more exaggerated. Thus the proposal is delayed to lull us into a false sense of security before shocking us.
First, and this is important, it is not "Swift's" plan that we are discussing, but that of his clueless narrator. Swift does not approve of this proposal and wants his readers to be horrified by it. Only the narrator, who is not Swift, thinks it is a good idea.
It is not until the ninth paragraph of this essay that we come to understand that the narrator is proposing that the poor sell their babies for food. It is here that he says he has learned from an "American" 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 fricassee or a ragout.
This is a shocking and nauseating proposal, and yet, although the narrator is clueless about the boundaries of common humanity, he is a good rhetorician. He does his best in the opening paragraphs to first use pathos—appeals to our emotions—and logos—appeals our logical, rational minds—to build support for the idea that the situation of the poor is urgent. He begins by painting a heartbreaking picture of a poor woman in rags trailed by her starving children and then convincingly shows that he has a grasp on the statistics about the number of poor and their prospects. This builds his credibility, and by the ninth paragraph, we are anxious to hear his proposal. The trouble is that it is heartless and barbaric.