The abuse of power
Who holds power, why they hold it, and how they use or abuse it, are recurring themes throughout Gulliver's Travels. The Lilluptians, despite their small size, wield considerable power over Gulliver, taking advantage of his well-meaning, non-aggressive, and gullible nature to attack him with arrows, hold him prisoner, and finally try to entrap him through treachery. Lilliput is governed by a vain and despotic ruler who has his subjects tortured and executed for trivial matters. His ministers are appointed to office not based on their suitability, wisdom, or virtue, but on their skill at "leaping and creeping." The correspondences between Lilliputian people and events and English political life means that Swift intended his portrayal of Lilliput to reflect abuses of power in the English monarchy and government.
The Brobdingnagians could, if they wished, dominate through their superior size, but they do not. Although they treat the relatively tiny Gulliver as a plaything and one of them, the farmer, is prepared to work him to death for personal gain, in general the Brobdingnagians do not abuse their power. The King of Brobdingnag is a wise ruler who only wishes to do good for his nation. When he is offered the secret of gunpowder, he refuses on humanitarian grounds, even though this would vastly increase his nation's power.
Swift implicitly questions the reasons why certain people hold power over others. The Laputan king assumes that he has a right to hold power over the Balnibarbians on the mainland simply because he is more devoted to abstract and theoretical knowledge than they are. To the reader, on the other hand, he appears ridiculously impractical and not fit to hold power. Similarly, the Laputans view Lord Munodi as hopelessly backward because he does not embrace the reforms of the professors of Lagado Academy; it seems likely that his estate and house will be seized by the government. The reader, however, can clearly see that common sense lies on the side of Munodi, and that if he held power, the kingdom would prosper.
A more ambiguous example of power is that wielded by the Houyhnhnms over the Yahoos. Difficult moral questions can be asked about whether the Houyhnhnms have the right to dominate and exploit the Yahoos because they are more rational, intelligent, moral, and virtuous. These qualities may take on a different light when seen from the point of view of the Yahoos, whose very right to exist is debated by the Houyhnhnms in their council.
The absurdity of pride
Many examples of misplaced pride occur in the novel. The Lilliputians are proud of their military capability, although if Gulliver-sized human beings launched an invasion they would be instantly crushed. Swift draws attention to the absurdity of their pride by having them arrange a military parade in view of Gulliver's exposed nether regions.
Gulliver's stay among the Brobdingnagians punctures human pride and vanity as it relates to appearance. Gulliver sees the bodily features and functions of the Brobdingnagians in magnified form. Hence he notes how even a woman who might appear beautiful to her similarly sized compatriots appears to him as a mass of unattractive huge skin pores and mountainous pimples, who is in the habit of voiding gallons of urine.
The Laputans are proud of their knowledge of mathematics and music and their habit of abstract contemplation, but the reader can see that these qualities only make them so impractical that their houses fall down, their clothes fail to fit, and their subjects starve.
Although Gulliver attacks pride in his final chapter, he fails to notice that he himself has fallen victim to it in his rejection of humanity on the grounds that they are Yahoos. His pride blinds him to genuine virtue, such as that of Don Pedro, and makes him cruelly reject his wife and family.
Excrement and bodily functions
Swift's emphasis on bodily functions and excrement provides a satirical counterweight to the tendency of his age, which championed man as a rational creature and became known as the Enlightenment. Swift was eager to remind humanity that underneath their pretensions to rationality and superiority, they were made of the same skin, blood, and bone as the animals, and shared their basic needs, appetites, and functions.
The individual and society
Most of the time during his travels, Gulliver feels isolated from the societies he visits. He does not fit in anywhere, and even during his brief returns to England, he expresses no wish to stay and leaves as quickly as he can. This has led to some critics calling Gulliver's Travels the first novel of modern alienation.
The country of the Houyhnhnms is unique among the nations Gullliver visits because of its subjugation of the individual to the good of society as a whole, which leads to an orderly and well-run nation. The price is that there is little room for human-style individuality. Nobody can become attached to their children because they may be assigned to another family that has a shortage of children; mates are chosen not by individual preference, but for the good of the race; servanthood is genetically mandated.
Only during his stay with the Houyhnhnms does Gulliver wish to assimilate into society. His attempts are ridiculous, leading to his taking on the gait and speech patterns of his horse hosts. More seriously, they are doomed to fail: the Houyhnhnms decide that he is not one of them and expel him. The only society to which Gulliver wishes to belong will not have him. Swift raises questions about the conflict between the individual and society, but does not resolve them.
Knowledge versus wisdom
Swift emphasizes in Gulliver's Travels that knowledge is not equivalent to wisdom. Certain Lilliputian politicians are knowledgable about the leaping and creeping necessary to gain power, but the people live in fear of their rulers' edicts condemning the innocent to death. Laputans study abstract mathematics and music, and research high-flown theories in their academy, while the ordinary people starve.