The important thing to remember is that Swift is writing a satire: he is making fun -- rather savage fun -- of human beings. He doesn't like people much and everything about the yahoos, who are so people-like that they are a metaphor for people, suggests his contempt and disapproval of how human beings have conducted themselves on the planet. His general contempt for people is seen in his portrayal of theYahoos, a people-like species so similar to people that we must take them as a metaphor for people.

His specific disapproval of people is seen in Gulliver's explanation to the Houyhnhnms of 1) war; 3) lawyers; 4) medicine and health.

We also see his disapproval of people in his creation of a superior animal race, the Houyhnhnms. The Houyhnhnms are entirely logical beings who have trouble understanding human doubting and not believing, of the use of clothes and wine, and the tolerance for the homeless.

Gulliver comes to despise his own species and to admire the Houyhnhnms so much that when he is forced to return home he insists on spending his time with his horses rather than his family.