It is right to kill an intending murderer supposing that there is no other way of preventing him from committing his crime, whether the intended victim be oneself or someone else. It is not only the life thus protected from attack that is saved, but the murderer in a sense is saved as well, so far as he can be saved, by the intervention. Also the members of his family are saved, humanity is saved from moral disgrace in his person. The same reasoning applies to the position of the extreme non-resistants. They will not, they tell us, do a wrong to prevent a wrong. In their eyes to take the physical life of another is in every possible instance an absolute wrong. They fail to take account of the instrumental relation between the physical and the spiritual parts. And on the same grounds, a defensive war, a war to ward off aggression, may be theoretically justified. But here the application of the theory is dubious as well as dangerous. Exceptional cases of high-handed aggression that ought to be resisted occur, but aggression is rarely, if ever, one-sided. As a rule, there is more or less wrong on both sides, and the tangle of accusations and mutual recriminations is almost impossible to unravel. Very rarely, indeed, if ever, is right altogether on one side, and wrong on the other, though predominant right may be on one side and predominant wrong on the other. And aside from this, the instruments of destruction in modern warfare have become so monstrous, the efficiency notion applied to war has led to such ruthlessness, the attempt to distinguish between the civilian population and the armed forces has so nearly broken down, that right-thinking persons everywhere are now eagerly intent on how to prevent aggression before it can take effect, rather than to resist it after it has occurred. NOTE The casuistical question may be raised whether from this point of view we are not all murderers. The amount I spend on my house, food, recreation, might if divided prolong the life of many a child in the slums. Am I not then actually a parasite, that is, a murderer? It is this shocking scruple that has led fine people to live among the poor, and to try to equalize their mode of living with that prevailing in the environment. The motive is noble, though as a matter of fact they may never succeed in doing what they set out to do because they never actually touch bottom. There are always depths of poverty to which they can not descend. They may spend comparatively little, yet that little is far in excess of the spending of the most indigent. And had they stripped themselves of everything they would have been face to face with the _reductio ad absurdum_ of their method, for they would have abandoned civilization and degraded their human life to the level of the wayside tramp. What is inspiring in their example is just the immense compassion, the willingness to give up so much. But the method itself is not a solution.