Explain the use of irony in Shirley Jackson’s “The Lottery” and how it helps to develop the story

The central irony in Jackson's "The Lottery" is that
normal people are capable of great brutality when that brutality is sanctioned by the
majority or by society. 

The irony is developed through the
use of point of view, setting, character behavior, and
foreshadowing. 

The limited point of view reveals only what
appear to be everyday, normal details.  The village appears normal (school has recently
let out, the kids think of school, people are in a hurry to get to lunch, they gather
for a summer festival of some kind), and no thoughts are revealed.  Thoughts, of course,
would give away the surprise ending. 

Foreshadowing makes
the surprise ending make sense, once it occurs.  The boys gathering stones, for
instance, seems harmless at the time, but gives the ending
legitimacy. 

The irony only becomes apparent when the
nature of the lottery is revealed, though.  Thus, it isn't that irony develops the
story, but that the story reveals the irony.  In some works, the irony does develop the
story.  In this case, however, the irony is revealed at the conclusion of the
story.