The themes in Shirley Jackson's scary short stories include the breakdown of social order. Take 'The Lottery' again; it shows how a long - held tradition can be so cruel yet blindly followed by the community. There's also the theme of the uncanny. Things that are almost familiar but with a strange and terrifying twist. And she often plays with the idea of the vulnerability of the individual in the face of collective madness or the unknown forces at work in the world.
One common theme is the sense of unease in ordinary settings. For example, in 'The Lottery', a small town with a seemingly normal annual event turns out to be extremely disturbing. Another theme is the power of social norms and how they can lead to cruel or unjust behavior. Also, the exploration of the unknown and the fear it brings, like in some of her stories where strange things start to happen in familiar places.