The Stanford Encyclopedia of Philosophy says: "The doctrine (or principle) of double effect is often invoked to explain the permissibility of an action that causes a serious harm, such as the death of a human being, as a side effect of promoting some good end. It is claimed that sometimes it is permissible to cause such a harm as a side effect (or 'double effect') of bringing about a good result even though it would not be permissible to cause such a harm as a means to bringing about the same good end." How has this principled used in analyzing real-world ethics? Is it true? Why or why not?