The 鉅子 (Juzi) is the head of the Mohist order. The title began with Mozi himself and passed in turn to 禽滑厘, 孟胜, 田襄子, and 腹䵍. Historically the 鉅子 was named by the predecessor and held enormous authority: Mohists obeyed the 鉅子's orders and would, as the saying went, walk into fire and boiling water without turning back.
Two stories survive about the historical 鉅子. In 381 BCE, 孟胜 was holding a city for the Lord of Yangcheng. The city could not be held, and he chose to die keeping faith. One hundred and eighty-three Mohists died with him, but first he sent messengers to pass the title to 田襄子 so the order would go on. Another 鉅子, 腹䵍, was living in Qin when his son killed a man. The king of Qin said: you are old, sir, and this is your only son; I have already pardoned him. 腹䵍 replied: the Mohists' law says who kills shall die, who wounds shall be punished. He had his son executed.
The two stories show two sides of the office: duty to the order outweighing one's own life, and duty to the rule outweighing one's own family. The 鉅子 stands not above the rules but under them.
In 墨门 today
墨门 keeps the title 鉅子 but changes how it is filled and how far it reaches.
Elected. The 鉅子 is chosen by chapter delegates at the 兼爱大会, not named by a predecessor and not appointed by the council. The term is five years, renewable once at most. The assembly may remove a sitting 鉅子 by a two-thirds vote.
Bound by the Handbook. The 鉅子's duties are to carry out the 墨者之法, preside over the 兼爱大会, convene the council, and speak for the Community. The 鉅子 cannot amend the Handbook; that power belongs to the assembly. The 鉅子 cannot draw on the care fund; funds are controlled by each chapter under open procedures. The 鉅子 cannot appoint chapter leads; chapters choose their own.
No doctrinal authority. This is the largest difference between 墨门 and the historical order. The 鉅子's reading of the Mozi is one reading, like any Mohist's. Whether a claim is right is settled by the three tests: precedent, evidence, benefit. What the 鉅子 says is not more right for having been said by the 鉅子.
Unpaid. Like chapter leads and council members, the 鉅子 serves as a volunteer.
We keep the title to remember 孟胜 and 腹䵍: one who valued the order above his life, one who valued the rule above his family. We narrow the office so that no one has to make such a choice again.