The trolley problem is a classic thought experiment in ethics, which asks you to imagine a trolley headed toward a track that five people are bound to. If you pull a lever, you can redirect the trolley to another track, where one person is bound. Do you do nothing at all and watch five people die? Or pull the lever, change fate and be personally responsible for the death of one person?
Source: Gizmodo – Two-Year-Old Prodigy Finds Viciously Perfect Solution to the Trolley Problem