Analytic philosopher is one of the most male-dominated fields in the academy, thus it is a point of pride that Oxford professor Philippa Foot invented the most famous ethics thought experiment of the 20th century: The Trolley Problem.
Foot asked us to imagine that a runaway trolley is barreling down a track with 5 people tied down to it. You are within reach of a lever that will switch the trolley to another track that only has one person tied down. Do you pull the lever?
Foot did not give a specific answer to the problem, because that would miss the point: the Trolley Problem addresses one of the fundamental issues of ethical disagreement: two people can be completely aware of the facts of a situations, and of the consequences of the choices, and still not come to an agreement. Thus, conflicts between parties can be a matter of values or principles that do not reduce to the physical facts.
In her other work, Foot would argue that ethics ought to be based on virtues (which have more to do with one’s character than particular actions), and that virtues are natural properties themselves.
Other philosophers took the Trolley Problem in their own direction, adding new complications. Perhaps the most interesting is Judith Jarvis Thompson’s (of the Violinist argument for the permissibility of abortion) addition of the Fat Man. Suppose a very fat man is standing on a bridge above the track. You know that if you push him, he will die, but he will stop the train from killing the five. Do you push him? Immediately, we are tasked with considering if there is a moral difference between the “Killing” of pushing the fat man, and the “letting die” of selecting the one to die over the five. Once again, “Solving” the Trolley Problem is not nearly as important as identifying the value conflicts that make ethical decisions difficult.
And as long as we are in the realm of hypothetical ethical consideration, yes, I would push the fat man to save five lives. But I would also consider that if we kept pushing people to their deaths to save others (e.i. utilizing torture, oppressive police techniques, unethical medical practices, irresponsible foreign policy), than perhaps we are not the bystanders, but rather, the villains who are tying people to the train track to begin.