Mozi (墨翟, Mo Di) lived in the fifth century BCE, in the early Warring States period. He was born around the time Confucius died and a century before Mencius. Reliable records of his life are scarce. He is usually placed in the state of Lu and associated with the area of Tengzhou in today's Shandong. He came from the artisan class and knew woodworking and mechanics; the Mozi is full of wheelwrights, carpenters, dye-vats, and carts, hardly the vocabulary of a noble scholar.
From Confucian student to founder
Mozi studied Confucian teaching in his youth. He came to think its rituals too elaborate, its burials a drain on the people, and its talk of fate an excuse for idleness, so he founded his own school. He summed up his teaching in ten doctrines: impartial care, against aggression, promoting the worthy, shared standards, moderation in use, simplicity in burial, the standard above, acting as if watched, against extravagance, against fatalism. One thread runs through all ten: promote what benefits the world and remove what harms it. Every proposal is measured by that.
His method for judging right and wrong is the three tests set out in 非命上: look for precedent in the sage kings, look for evidence in what ordinary people see and hear, and look at the results when a claim is put into practice. It is the first explicit standard for testing claims in Chinese thought.
Stopping the attack on Song
Mozi's most famous deed is told in the 公输 chapter. Gongshu Ban had built scaling ladders for Chu, which was preparing to attack Song. Mozi set out from Lu and walked ten days and nights to the Chu capital, Ying. First he argued Gongshu Ban into admitting the attack was wrong. Then, before the king, with his belt as a wall and wooden chips as engines, he held off nine assaults. Gongshu Ban said he had one more method. Mozi knew it meant killing him, and answered that 禽滑厘 and three hundred followers were already on the walls of Song with his defensive devices. The king gave up.
The story holds Mozi's whole method: argue first, prepare second, make attack not worth it.
Organization and discipline
Mozi was not only a thinker. He built a disciplined order whose members were called Mohists and whose head was the 鉅子. Mohists who took office in various states remitted part of their salary to the order, and those who violated its teaching were recalled. When 胜绰 helped Qi wage aggression, Mozi said "his pay outweighed his principles" and called him back. The Mohists' law held that "who kills shall die, who wounds shall be punished," and a later 鉅子, 腹䵍, had his own son executed under it. The Mohists were the age's finest siege-defense engineers; the Mozi's last twenty chapters are their manual.
Mozi died around 391 BCE. Mencius said of him that if wearing himself down from crown to heel would benefit the world, he would do it. Han Fei named Confucians and Mohists the two prominent schools of the age. After his death the school split into three lineages, produced the Canons on logic, geometry, and optics, and disappeared after the Qin and Han.
Why read him now
What Mozi left is not a creed but a method: put every person's welfare on the same scale, test every claim by precedent, evidence, and result, give responsibility to those who can carry it, and act as if watched. None of this asks you to believe anything. It only asks you to do it.