Principle is likewise such a law for action, except that it has not the formal definite meaning, but is only the spirit and sense of law in order to leave the judgment more freedom of application when the diversity of the real world cannot be laid hold of under the definite form of a law. As the judgment must of itself suggest the cases in which the principle is not applicable, the latter therefore becomes in that way a real aid or guiding star for the person acting.
Principle is objective when it is the result of objective truth, and consequently of equal value for all men; it is subjective, and then generally called maxim if there are subjective relations in it, and if it therefore has a certain value only for the person himself who makes it.
Rule is frequently taken in the sense of Law, and then means the same as Principle, for we say “no rule without exceptions,” but we do not say “no law without exceptions,” a sign that with Rule we retain to ourselves more freedom of application.
In another meaning Rule is the means used of discerning a recondite truth in a particular sign lying close at hand, in order to attach to this particular sign the law of action directed upon the whole truth. Of this kind are all the rules of games of play, all abridged processes in mathematics, &c.
Directions and instructions are determinations of action which have an influence upon a number of minor circumstances too numerous and unimportant for general laws.
Lastly, Method, mode of acting, is an always recurring proceeding selected out of several possible ones; and Methodicism (METHODISMUS) is that which is determined by methods instead of by general principles or particular prescriptions. By this the cases which are placed under such methods must necessarily be supposed alike in their essential parts. As they cannot all be this, then the point is that at least as many as possible should be; in other words, that Method should be calculated on the most probable cases. Methodicism is therefore not founded on determined particular premises, but on the average probability of cases one with another; and its ultimate tendency is to set up an average truth, the constant and uniform, application of which soon acquires something of the nature of a mechanical appliance, which in the end does that which is right almost unwittingly.
The conception of law in relation to perception is not necessary for the conduct of War, because the complex phenomena of War are not so regular, and the regular are not so complex, that we should gain anything more by this conception than by the simple truth. And where a simple conception and language is sufficient, to resort to the complex becomes affected and pedantic. The conception of law in relation to action cannot be used in the theory of the conduct of War, because owing to the variableness and diversity of the phenomena there is in it no determination of such a general nature as to deserve the name of law.
But principles, rules, prescriptions, and methods are conceptions indispensable to a theory of the conduct of War, in so far as that theory leads to positive doctrines, because in doctrines the truth can only crystallise itself in such forms.
As tactics is the branch of the conduct of War in which theory can attain the nearest to positive doctrine, therefore these conceptions will appear in it most frequently.
Not to use cavalry against unbroken infantry except in some case of special emergency, only to use firearms within effective range in the combat, to spare the forces as much as possible for the final struggle—these are tactical principles. None of them can be applied absolutely in every case, but they must always be present to the mind of the Chief, in order that the benefit of the truth contained in them may not be lost in cases where that truth can be of advantage.