“Simulated disorder postulates perfect discipline; simulated fear postulates courage; simulated weakness postulates strength.”
To fake weakness convincingly you must truly hold strength; the pretense is proof of the real thing.
Chapter 5 states the prerequisite of every feint: simulated disorder postulates perfect discipline; simulated fear, courage; simulated weakness, strength. Postulates — in the mathematical sense of what must already be true for the thing to work. Sun Tzu is auditing deception for the reader: every convincing false signal is broadcast from a real and opposite capacity.
A founder lets a competitor believe the startup is desperate for its next round — quiet layoffs rumored, a slow quarter hinted. The bluff works for a month. Then the competitor tests it, poaching a key engineer with an aggressive offer, and the "weak" company cannot counter — because it was. The simulated weakness that would have masked a fortified balance sheet instead confirmed an empty one; the pretense was a loan against strength that did not exist.
The verse is often read as a license to bluff — it is the opposite: a proof that bluffing fails. Fake it without the underlying capacity and the first contact calls the bluff. The legitimate use is narrower and more interesting: displaying less than you hold, which requires the holding. The poker term is not "lying"; it is "under-betting."