Swift is using Gulliver's voyages to satirize various aspects of English society. Gulliver's various conflicts in the lands he visits allow Swift to discuss a number of problems he sees with English society and the way England is governed.
When Gulliver washes ashore on Lilliput, for example, he soon observes that the Emperor of Lilliput chooses his ministers not on the basis of their ability to govern but on their ability to walk a tightrope. This is Swift's thinly-veiled criticism of how George I, the King of England, chooses his ministers--in this case, not on their ability to walk a tightrope but on their connections within the court and whether or not they will make decisions based on what King George wants them to do rather than on what is right for the English. In another instance, Swift, through Gulliver, criticizes the religious animosity within English society by telling us about the hatred between those Lillitputians who open their eggs from the small end or the large end first. The point is, of course, that it doesn't matter what end one opens an egg, but Swift is pointing out how ridiculous some controversies are.
Again, in the third voyage, to the island of Laputa, Gulliver discovers a race of people who are so detached from reality that they require their servants to carry inflated bladders and hit them in order to remind them bring them back from highly speculative thought to real-world concerns. Gulliver tells us, for example, that some of these people are actually trying to build a house from the top down, a physical impossibility, but symptomatic of how removed from everyday reality these people are. Swift is satirizing the over-abundance of genuine "projectors" in England who were constantly coming up with outlandish and unworkable ways to cure society's problems.
When Gulliver lands in the land of the Houyhnhnms, he discovers a race of horses who are perfectly rational, unemotional, logical beings, and the uncivilized brutes of this society, the Yahoos, are human beings. During this experience, Gulliver actually loses his own identity and considers himself a kind of Houyhnhnm rather than a human being, and when he returns to England, he can barely stand being around people, preferring horses for company. Swift is satirizing anyone who chooses a philosophy over reality.
In the end, Swift has managed--through the framework of a child's fairy tale--to point out many problems in English society that need correction, and he has accomplished this without pointing overtly to specific people within English society.
Jonathan Swift was one of the leading satirists in English literature. In Gulliver's Travels, he satirizes many aspects of literature, politics, religion, and philosophy, even critiquing the "tall tale" or travel adventure story itself.
Swift, who became Dean of St. Patrick's Cathedral in Dublin, was especially concerned with the way that factions within the Church of England and the opposition of the Anglican Church to Roman Catholicism in Ireland had a negative effect on the church's greater mission of spreading Christianity and caring for the poor and oppressed. He viewed many of the theological and liturgical quibbles as silly. This attitude is reflected in his description of the Big-Endian/Little-Endian controversy.
Swift was also satirizing the prevalence of patronage and corruption in politics. When Gulliver first visits Lilliput, he observes a show in which aspiring politicians perform acrobatic tricks to gain political favor. This echoes his feeling that what really should matter are sound ideas and experience rather than flattery and patronage. In this, Swift reflects some of the points made by his patron, William Temple, who was especially concerned with government reform and diplomacy.
Swift also satirizes pointless abstract speculation and science in his treatment of Laputa. In his presentation of the Houyhnhms he satirizes philosophy and the arts.
In Gulliver's Travels, Swift manages to satirize politicians, religion, science, society and even the king of his age.
During the first voyage, Swift satirizes political conditions when Gulliver comes to know that the king of Lilliput chooses his ministries not on the basis of their political skills but on their ability to dance on a tight rope.
He criticizes religious conditions when he comments on the Lilliputians' religious division between those who wear low-heeled and high-heeled shoes. and who open their eggs from the small and the large end.
The cultural satire comes in the fourth voyage where Gulliver goes to the land of Houyhnhnms. In fact, these Houyhnhnms are rational horses and their servants are Yahoos who are presented as human beings. The difference between Yahoos and Houyhnhnms allows Swift to criticize the nature of man more closely than in any other voyage.
In writing Gulliver's Travels, Swift had aimed at amending and correcting his public. He wanted to shock the people into a realization of their faults and failings.
Gulliver's Travels is an allegorical satire. this mean that Swift does not attack personalities and institutions directly but in a veiled manner.
In Gulliver's Travels, Gulliver especially singles out "pride" as the greatest defect of human being. When Gulliver has become an absolute and uncompromising hater of mankind and even of his own family, Swift is not to be identified with him. Here Swift seemed to be point out to us the dangers of extreme misanthropy.
Although Jonathan Swift criticized human being strictly, his aim was to alert mankind to their faults and failings.