According to official SWIL policy (of which there is very little), SWIL is "a nondeterministic set of sentients devoted to order and chaos." We also tend to like science fiction.
According to most of the population of Swarthmore, SWIL is a strange group of people that is possibly sane (or possibly not) and quite possibly not from this world at all.
According to SWILies, SWIL is a group of people that's usually fun to be around, although can get rather tiring after too long, which engages in a variety of activities. Also, SWIL is a good way to get to know Swat alums (known as "dinosaurs") since they tend to hang around for a while after graduation and still come back for the occasional gaming session (or two, or three, or four....).