Definition
Flexibility in tactics — Sun Tzu's "Nine Contingencies" or "Nine Variations" — is the meta-rule that every other rule in the book is conditional on. Articulated in Topic 8 of The Art of War, the principle states that the situation has primacy over the principle: even the most reliable strategic maxim has cases where breaking it is correct.
The catalogue of refusals is famous:
- Roads he will not travel.
- Armies he will not strike.
- Walled cities he will not attack.
- Terrain he will not contest.
- Ruler's commands he will not obey.
The last is the most radical: a commander in the field has information the ruler does not, and an order based on incomplete information should sometimes be refused. Authority does not erase responsibility.
Why it matters
How it works
Flexibility operates by holding the principle and the situation separately. The principle says "take the high ground first"; the situation says "but this particular high ground is a trap." The skilled commander knows the principle deeply enough to know when it does not apply. The inexperienced commander either follows the principle into the trap or abandons all principles and operates on instinct.
The discipline is paired with a corresponding warning: the five fatal flaws (Topic 8's closing list) are all forms of inflexibility — the reckless commander who can only attack, the cowardly one who can only retreat, the hot-tempered one who can only react, the vain one who can only protect his reputation, the over-compassionate one who cannot enforce. Each flaw is a single mode the commander cannot deviate from. The skilled opponent identifies which one applies and arranges the contest around it.