What technique does Swift use in Gulliver's Travels to produce satire?
The satirical technique Swift uses "Gulliver's Travels" is to attack modernity. He is concerned about the increasing power of Europe throughout the world, the pettiness of the elite, and the growing focus on money for fulfillment in life.
Swift makes the reader consider these problems by just the things you mention in your note: reductionism, absurdism, and defamiliarization. Reductionism takes large problems and reduces them to small ones. For example, we see how foolish and petty the Lilliputions act as they battle with the neighboring country over nothing at all. Their squabbling is reflective, reducing the problems of European colonization of the world in this microcosm.
Absurdism in found everywhere in this book, from beginning to end, whether it is the relatively giant Gulliver being tied up by the diminutive Lilliputians and subdued by their annoying arrows, Gulliver being transported in a doll house in Brobdingnag, talking horses or men reduced to apes.
The absurdism is used to defamiliarize the reader and make him/her see the real situations with new eyes. Like all satire, the parallels to the real world will be more powerful when realization that "this is us" finally hits.
The purpose of satire is to expose the folly of aspects of society in which the writer finds in need of change.
The techniques of satire include hyperbole, slapstick, incongruity, and irony. Swift is a master at weaving these techniques into his work. For example, in book one Gulliver agrees to demands on his freedom when he clearly could destroy all of the citizens of Liliput if he wanted to. This example of situational irony is Swift's way of pointing out the ineffective nature of the "modern man" which Gulliver represents. Also notice the scene where Gulliver urinates on the queen's palace to put out a fire. The outrageous nature of this act and the object of the satire should be somewhat obvious. Topically, Swift was criticizing Queen Anne and her distace for Swift's work. He is using a gross exaggeration (hyperbole) to prove a point.
His most biting satire in the book is when Gulliver travels to the land of the Yahoos. It is at this point that Gulliver realizes that he is nothing but a Yahoo and he can never fully recover from the shock.
Another text by Swift which has good example of the above mentioned satirical techniques in "A Modest Proposal."