Chinese idiom · 成语
师出无名
Meaning
An army marches without cause; unjustified action.
Character by character
Origin and story
Political expressionEarly discussion in the Liji (禮記), Tan Gong II, links a military expedition with having a publicly defensible reason: a ruler’s punishment and subsequent mercy are discussed as grounds that give the campaign its name or justification. 名 in this setting is not merely the name of an army.
The complete negative expression appears in Pei Ziye’s essay on the three rebellions of the Taishi period, criticizing an expedition without sufficient justification. The Old Book of Tang likewise warns that launching troops over a minor grievance can endanger the attacker. From this political language comes the broader idiom: taking action without a sound reason that one can explain to others.
Sources and further reading
In everyday life
没有违反约定就扣押金，房东这样做未免师出无名。
Withholding the deposit when no agreement was broken would leave the landlord without a valid justification.
Extends beyond armies to actions lacking an adequate stated basis; critical in tone.