Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
Deadpan, Detached, Calm
Jackson's removed tone serves to underscore the horror of the lottery—there's no shift in narrative voice when the story shifts profoundly from generic realism to nightmarish symbolism.
We go from reading about a small village on a sunny summer day to witnessing the villagers execute a member of their own community, all without the slightest change in tone form the author.