Duty to rescue
Utilitarianism: utilitarianism posits that those actions are right which best maximize happiness and reduce suffering ("maximize the good").  Utilitarian reasoning generally supports acts of rescue which contribute to overall happiness and reduced suffering.  Rule utilitarianism would look not just at whether individual acts of rescue maximize the good, but whether certain types of acts do so. It then becomes one's duty to perform those types of actions. Generally, having strangers rescue those in distress maximizes good so long as the rescue attempt does not make things worse, so one has a duty to rescue to the best of her or his ability as long as doing so will not make things worse.