Let's see: the poor citizens of Ireland are fed to the wealthy elite. Yep, class divisions play a major role in A Modest Proposal. More specifically, there's a debate going on over who should take responsibility for society's welfare. Should landowners take it easy on their starving tenants? Swift weighs in by sketching out an alternate society in which the rich dehumanize their fellow countrymen. His point is more than a little bit sinister: as the Irish population spirals out of control, it's increasingly easier to see a person as a statistic.
A Modest Proposal is meant to show us that class is an artificial construct. Poor children are just as deserving as wealthy children.
Swift suggests that those who possess the most wealth have a responsibility to their less fortunate countrymen. They should turn their attention from pride and vanity to charity.