It is hard to know how every individual will respond to "A Modest Proposal," but it seems very unlikely that many people in Swift's day would have taken it seriously. Remember that Swift's essay was aimed at an educated readership, people who would have been well-versed in both the essay format of argumentation and in the use of satire which Swift carried to new extremes with "A Modest Proposal." In fact, some literary critics have argued that, because its proposal was so patently absurd, Swift's essay was actually less sophisticated a satire than some other works, like those of Alexander Pope. But it is worth noting that it was a powerful satire on a number of levels, criticizing the overly scientific "political economy" solutions to social problems offered by many educated men as well as the effects of British colonialism on the Irish poor. What aspects of the essay resonated with people largely depended on the reader. As a side note, from personal observation, I have used this text with many different students, ranging from high school freshmen to college students, and I do not recall that any failed to "catch on" to the joke at some point.