The doctrine that it makes an ethical difference whether an agent actively intervenes to bring about a result, or omits to act in circumstances in which it is foreseen that as a result of the omission the same result occurs. Thus suppose I wish you dead, if I act to bring about your death I am a murderer, but if I happily discover you in danger of death, and fail to act to save you, I am not acting, and therefore according to the doctrine not a murderer. Critics reply that omissions can be as deliberate and immoral as commissions: if I am responsible for your food and fail to feed you, my omission is surely a murder. The question is whether the difference, if there is one, between acting and omitting to act can be described or defined in a way that bears general moral weight. See also double effect, trolley problem.
Philosophy dictionary. Academic. 2011.