In "A Modest Proposal," how does Swift use pathos to enhance his argument?

Pathos is emotional appeal, and Swift's narrator spends the opening paragraphs of "A Modest Proposal" painting a heart-rending picture of the plight of the Irish poor. The narrator appears quite moved by their situation, describing "the streets, the roads and cabbin-doors crowded with beggars of the female sex, followed by three, four, or six children, all in rags," followed by noting that some of the people are so desperate they sell themselves into slavery or commit infanticide because they can't support their children The narrator invites us into compassion with the poor and talks in reasonable terms about being sure everyone wants a solution to the problem of poverty. Having drawn a vivid portrait of a country overrun with ragged, begging women and children, the narrator's "proposal" then shocks all the more in its hard-hearted rationalism. Our feelings of compassion and pity having been aroused for the poor, it is all the more repulsive to us to contemplate eating their one-year-old babies.

Later in the essay, Swift use pathos to describe the plight of the older poor in a way they raises our pity:

Some persons of a desponding spirit are in great concern about that vast number of poor people, who are aged, diseased, or maimed; and I have been desired to employ my thoughts what course may be taken, to ease the nation of so grievous an incumbrance. But I am not in the least pain upon that matter, because it is very well known, that they are every day dying, and rotting, by cold and famine, and filth, and vermin, as fast as can be reasonably expected. And as to the young labourers, they are now in almost as hopeful a condition. They cannot get work, and consequently pine away from want of nourishment, to a degree, that if at any time they are accidentally hired to common labour, they have not strength to perform it, and thus the country and themselves are happily delivered from the evils to come.

However, the narrator, having painted such a picture of suffering, dismisses it: these people are already dying quickly, he says, so not to worry. Again, the juxtaposition of pathetic descriptions of the dying poor and the narrator's cold-hearted contention that their death solves our problems jars and upsets us. 

Needless to say, Swift used pathos on purpose to heighten the effect of his essay.