The purpose of "The Lottery" is related to the themes that Shirley Jackson develops in the story. One of these themes has to do with the nature of customs, traditions, and rituals. The story questions people's practice of blind adherence to traditions even when these traditions prove harmful to those who practice them. In "The Lottery," the villagers do not remember how the lottery started nor what it is supposed to represent. Even the eldest villager Old Man Warner cannot explain the significance of the lottery--he simply supports keeping the tradition going because it part of their custom and he is resistant to change. When Tessie is chosen as the one to be stoned, she claims that it is not fair--but would it be more fair for someone else to have been chosen? Jackson's story poses this question, and thus the purpose of the story is for readers to consider their position on custom and tradition.
The purpose of the story is to show how individuals can get so caught up in tradition they will continue to do it even if it kills.