Propaganda can be conducted by rule of thumb. But only a genius can make it work well by playing his hunches. It can become true psychological warfare, scientific in spirit and developed as a teachable skill, only by having its premises clearly stated, its mission defined, its instruments put in systematic readiness, and its operations subject to at least partial check, only by the use of techniques borrowed from science. Of all the sciences, psychology is the nearest, though anthropology, sociology, political science, economics, area studies and other specialties all have something to contribute; but it is psychology which indicates the need of the others. =Psychological Warfare as a Part of War.= An infantry officer does not need to study the whole nature of war, in order to find his own job. Tradition, military skill, discipline, sound doctrine--these have done the job for him. Sun Tzu, Vegetius, Frederick, Clausewitz and a host of lesser writers on war have established the place of combat in war, and have appraised its general character. How much the traditional doctrines may be altered in the terrible light of atomic explosion, no one knows; but though the weapons are novel, the wielders of the weapons will still be men. The motives and weaknesses within war remain ancient and human, however novel and dreadful the mechanical expedients adopted to express them. Warfare as a whole is traditionally well defined, and psychological warfare can be understood only in relation to the whole process. It is no mere tool, to be used on special occasion. It has become a pervasive element in the military and security situation of every power on earth. Psychological warfare is a part of war. The simplest, plainest thing which can be said of war--any sort of war, anywhere, anytime--is that it is _an official fight between men_. Combat, killing, and even large-scale group struggle are known elsewhere in the animal kingdom, but war is not. All sorts of creatures fight; but only men declare, wage, and terminate war; and they do so only against other men. Formally, war may be defined as the "reciprocal application of violence by public, armed bodies." If it is not _reciprocal_, it is not war, the killing of persons who do not defend themselves is not war, but slaughter, massacre, or punishment.