In Jonathan Swift's Gulliver's Travels, how does Swift illustrate his moral criticism of his world as the thematic link among the stories.
Gulliver's Travels seems to be a series of stories apparently lacking a coherence or thematic link among them. But it must have to be there to organize a significant plot.
During each voyage, Dr. Gulliver comes discovers a race of people more like Europeans but who engage in some behaviors--either very positive or negative--that allow Swift to comment on 18thC. English society or European society as a whole.
When Gulliver is in Lilliput, for example, he discovers that the Emperor chooses his counsellors not on the basis their inherent abilities to govern the island but on their ability to walk a tightrope successfully. This is a not-so-veiled criticism of how ministers in King George's government are chosen--not primarily because they can govern well but on the basis of their family connections and willingness to accede to the King's wishes.
In the land of the Brobdingnags, whose king is a highly educated philosopher, well-versed in governance, Gulliver spends a great deal of time describing European society, culture and politics, including warfare, all in an attempt to impress the King with English and European advancement. Gulliver's prideful descriptions of European excellence, however, draw this conclusion from the King:
I cannot but conclude the Bulk of your Natives, to be the most pernicious Race of little odious Vermin that Nature ever suffered to crawl upon the Surface of the Earth.
Again, by establishing the rational and learned views of the Brobdingnag King, who then concludes that Europeans, specifically, the English, are "little odious Vermin," Swift makes a powerful statement about the moral underpinnings (or lack thereof) of English society.
The third voyage allows Swift to criticize, among other things, preoccupation with esoteric scientific pursuits to the exclusion of ruling and governing well. When Gulliver meets the Laputian King, for example, the King is so absorbed in his instruments that servants have to gently hit him with an air-filled bladder to get the King's attention on Gulliver. The Laputians are so immersed in intellectual matters that a servant with a bladder is required to walk with them and tap them to get their attention just before they walk over the edge of a cliff. They tend to despise practical applications of mathematical principles like geometry, so the walls of their houses are never quite at right angles to one another. In another land, Gulliver meets a people who do nothing but think up unworkable projects like building a house starting with the roof. Clearly, Swift is satirizing the number of projectors in England who create unworkable solutions to real problems--Irish poverty, for example.
When Gulliver arrives in the Land of the Houyhnhms, the rational, unemotional horses who use men, called Yahoos, as their work force, Gulliver falls in love with the way the Houyhnhms live in pure harmony based on reason and a lack of emotion. This is contrasted with the Yahoos whose passion and emotions make them wild, almost ungovernable--in other words, very much like modern Europeans at their worst.
Swift's satire in Gulliver's Travels, depending on the seriousness of the target, is either gentle or harsh, but the novel is filled with implicit and explicit criticism of English and European society, and this satire, which is designed to correct problems, got the attention of Swift's readers in 18thC. England.