Sun Bin 孙膑

Descendant of Sun Wu, Strategist of Qi · 孙武后裔·齐国军师 · c. 4th century BCE · Sun Bin's Art of War《孙膑兵法》

School of Military Thought Indirection Momentum

Core Proposition · 核心命题

批亢捣虚。

Strike the vital point and the empty place. Sun Bin never meets strength with strength: instead of reinforcing the point under attack, threaten what the enemy must defend — and the enemy's own commitment becomes his trap. The indirect approach works because it converts momentum into vulnerability: an army locked into a siege is hostage to anything that forces it to lift that siege (形格势禁，则自为解耳). His book was lost for over a millennium and recovered only in 1972, from bamboo slips unearthed at Yinqueshan (银雀山) — until then, his thinking survived mostly inside the Shiji's battle narratives.

Mental Models · 思维原则

Principle 01

Besiege Wei to Rescue Zhao 围魏救赵

In 354 BCE, when Wei laid siege to Zhao's capital, Sun Bin did not reinforce Zhao — he struck Wei's own emptied capital, Daliang, and the siege dissolved by itself; Pang Juan raced home and was beaten at Guiling (桂陵). The mechanism: never meet the attack head-on; strike what the enemy must save (攻其所必救), and his attack loses its reason to exist. Direct relief accepts the enemy's chosen battlefield; the indirect move steals the initiative and makes him fight at your time, on your terms.

Principle 02

The Vital and the Empty 批亢捣虚

「批亢捣虚，形格势禁，则自为解耳。」Every committed force has an exposed throat — the point it cannot defend precisely because its strength is elsewhere. The strategist's work is to find the intersection of must-defend and cannot-defend (必攻不守): the vital place the enemy is forced to rescue, held open by his own commitment. Strike there, and his position locks itself — no battle is needed for the siege to dissolve.

Principle 03

The Diminishing Stoves 减灶计

At Maling (342 BCE), Sun Bin fed Pang Juan — the man who had framed him and had his kneecaps removed — a story in numbers: a hundred thousand cooking fires the first night, fifty thousand the second, thirty thousand the third. Pang Juan read the fires as mass desertion, abandoned his infantry, and raced ahead into an ambush beneath a tree carved with 「庞涓死于此树之下」. The mechanism is manufactured interpretation: you do not deceive the enemy's eyes, you deceive his reasoning, by confirming what he already wants to believe.

Principle 04

Attack the Undefendable 必攻不守

「必攻不守，兵之急者也。」Offense is defined not by your strength but by the enemy's undefendable points — the places where defense is structurally impossible because his force is committed elsewhere. Sun Bin's method inverts the amateur's question: instead of asking where the enemy is strong, ask where he cannot be strong, and make everything flow toward that point. Strength struck directly is heroism; weakness struck deliberately is arithmetic.

Key Passage · 原文

「夫解杂乱纷纠者不控卷，救斗者不搏撠。批亢捣虚，形格势禁，则自为解耳。」

He who untangles a snarl does not clench his fist into it; he who breaks up a brawl does not strike into the thick of it. Strike the vital point and the empty place — once form and momentum lock the enemy in place, the siege dissolves by itself.

Records of the Grand Historian · Biographies of Sunzi and Wuqi《史记·孙子吴起列传》

Modern Mapping · 现代映射

Competitive Strategy · 竞争战略

When a rival attacks your market, the amateur reinforces the point under attack — matching features, matching prices, fighting on the invader's terms. The 围魏救赵 move is to strike what the rival must save: its profit stronghold, its flagship customers, its talent bench — and watch the attack lose its funding. 「攻其所必救」 works because every committed competitor is hostage to whatever forces it to reallocate; the defense is decided not where the battle is fought, but where the rival's economics live. Direct relief wins a battle; the indirect strike dissolves the war.

Negotiation · 谈判

「批亢捣虚」 in negotiation means never arguing the contested point head-on; it means finding the counterpart's exposed throat — the must-have he cannot afford to lose — and shaping the entire deal around it. Leverage lives at the intersection of what the other side must rescue and what you happen to control; once you hold that, his position locks itself (形格势禁) and concessions arrive without a fight. The skilled negotiator spends the preparation phase mapping necessities, not positions: positions are where he argues, necessities are where he bleeds. Whoever controls the must-have controls the table.

Product Strategy · 产品战略

「必攻不守」 is the strategist's answer to the incumbent's advantage: do not attack where defense is possible — attack where defense is structurally impossible. An incumbent cannot answer the low-margin, unglamorous segment without cannibalizing its own flagship; its strength is committed elsewhere by design (形格势禁). The entrant's job is to find the point the incumbent must eventually rescue but cannot defend today, and to be entrenched there when the rescue finally comes. Products win not by out-featuring strength, but by making strength irrelevant.

Decision-Making · 决策

The 减灶计 is a masterclass in biased interpretation: Pang Juan did not see the fires, he saw his own expectation of Qi cowardice confirmed in numbers. The modern mechanism is identical — rivals, markets, and committees read signals through their priors, so the strategist designs signals that confirm the reader's overconfidence and induce overextension. Never correct a counterpart who is misreading you in your favor; feed the misreading one more data point. Pang Juan abandoned his infantry because the story was too clean — 「庞涓死于此树之下」 was carved before he ever reached the tree. The trap was built inside his own reasoning.