The tradition of "The Lottery," in which a random villager is stoned to death to promote a good harvest season, is ingrained in everyone practically from birth. For this reason, even rational people find nothing wrong with the practice. Even Tessie only objects because she doesn't think the lottery was performed correctly. When Mr. Adams mentions that another village is thinking of stopping the tradition, Old Man Warner (who has been through the lottery seventy-seven years) treats the idea with contempt:
"Pack of crazy fools," he said. "Listening to the young folks, nothing's good enough for them. Next thing you know, they'll be wanting to go back to living in caves, nobody work any more, live hat way for a while. Used to be a saying about 'Lottery in June, corn be heavy soon.' First thing you know, we'd all be eating stewed chickweed and acorns. There's always been a lottery," he added petulantly.
(Jackson, "The Lottery," Google Books)
Warner's thought is that the lottery is simply part of life. It should be conducted because it has always been conducted, and there are no moral arguments against it. His reasoning is based in stubborn ignorance: it is obvious that a ritual human sacrifice will have no real effect on the harvest, and it ingrains accepted brutality into the participating children. However, Warner's views are the majority opinion; nobody thinks it is wrong simply because it has always been done. The risk of keeping old traditions for their own sake (shown in how much of the "old ritual" has been forgotten) is therefore one theme of the story, and shown explicitly in Warner's statement.