In Book 2 On the Theory of War, Clausewitz states that reflections on the events of war led to the need for a theory due to controversies in military history, conflicting opinions and lack of basic principles and laws.
He then investigates efforts to bring principles and rules to the conduct of war and noted that these principles pertained only to physical matters and uniltaeral activity, the theorists who tried to resolve the problems, understand history and provide a theory considered only mathematical calculations and material factors such as:
1. Numerical superiority as the one and only rule
Or
2. Supply as the main issue in the conduct of war
Or
3. Geometrical principles
Clausewitz objected to all of these attempts because they didn't consider several important facts:
1. In war everything is uncertain.
2. All military action pertains to physical AND moral forces.
3. War is a continuous interaction of opposing forces that react.
He then went on to say that a commander can't rely on support at ALL times on manuals containing principles and rules, he must at times fall back on what he called talent, which is outside of manuals and conflicts with it. Talent and genius operate outside rules and therefore theory conflicts with practise. He is alluding to the theories he mentioned in his investigation that rely only on physical unilateral action and material factors that provide precise rules in the sense of a manual)
Clausewitz went on to discuss two alternatives to this problem (theory conflicting with practise).
1. Comments on the nature of military action in general do not apply to action at all levels. Tactics presents fewer difficulties than strategy because it mainly deals with physical forces that can be seen, whereas strategy deals mainly with the intellect and things based on uncertaintly such as influencing the commander's will.
2. As quoted in my previous post "27 Theory must be of the nature of observation, not doctrine", here Clausewitz states that theory does not have to be a manual for action. That inquiry is the most essential part of any theory and leads to becoming closer to the subject, where it is applied to military history it leads to familiarity. The closer it leads to familiarity the more effective it becomes in areas where rules and principles are not useful and instead one has to rely on talent.
After, he writes that theory studies the nature of ends and means and discusses this in relation to tactics and strategy.
Later, when discussing the nature of knowledge in relation to the commander in chief, he writes:
"The knowledge needed by a senior commander is distinguished by the fact that it can only be attained by a special talent, through the medium of reflection, study and thought: an intellectual instinct extracting the essence from the phenomena of life,..."
