In "The Lottery," one of the main ideas presented is the fact that all humans are ultimately on their own, and are responsible only for themselves. The story shows how solidarity is inexistent in this town, as no one is willing to defend those who are chosen in the lottery. This is likely a critique of the period of the two World Wars. During this time period, individualism became more prominent, and solidarity became less common.
The story is also a critique of mob mentality and the value of tradition. Despite the fact that the lottery is an outdated, damaging tradition, people feel forced to carry it out due to social expectations. Social pressure had also been prominent in past years, particularly during the Holocaust, where many common people committed horrible acts of cruelty due to tradition and social expectations.