The Doctrine of Double Effect is an ethical principle that is used to explain how certain actions that would cause considerable harm can be morally permissible where the bringing about of such harm is a side effect of the promotion of some good end. This principle is usually invoked by ethicists who subscribe to a deontological, or rule-based, approach to ethics, especially those who subscribe to the Judeo-Christian ethical tradition. (Indeed, Thomas Aquinas is credited with developing the first formulation of this Doctrine in his discussion of self-defense in the Summa Theologica.) Such ethicists are unwilling to hold that the good that could be brought about by the infliction of such harm would itself justify the bringing about of the harm, as would, for example, ...