北宋採行募兵體制，軍費構成政府在財政上沈重的負擔，引發諸多批判。但是，宋人的議論中仍有肯定募兵政策的論點，認為透過召募無賴之徒，加以軍法控制，有利於社會安定，正是宋太祖創設募兵制的目的。現代學者根據這些意見，主張「養兵」為宋太祖安定社會的手段，為其後代子孫所繼承。本文透過探討北宋君臣對於兵制的爭議，追溯宋代肯定募兵論述形成的過程。以王安石為代表的民兵論者，企圖推行義勇、保甲的體制來取代募兵，主要的理由在於召募的士兵多來自社會上的無賴之徒，平時消耗政府財源，戰時又無力抗敵。解決之道是恢復「三代兵農之法」，透過組織農民為兵，取代召募而來的「正兵」。與王安石立場相異的官員，則認為訓練平民為兵將會增加人民反抗政權的能力。基於此種疑慮，支持募兵制的官員發展出召募無賴為兵有利於社會安定的說法，並歸功於宋太極的創制，藉以塑造本朝優於前代的典範，來對抗王安石等人復行「三代之制」的訴求。神宗在元豐五年提出太祖以無賴為兵，藉其力以保衛良民的說法，是合理化募兵制的重要論點。此後，「養兵衛民」的論點成為統治者合理化軍費支出的依據，並形成與「兵農合一」相對立的兵制傳統。

During the Northern Song dynasty (960-1127), mercenary soldiers made up a major portion of the military and their salaries became a heavy, burden on the government. This phenomenon triggered debates about the military system among the ruling elite. While many Song bureaucrats urged their emperors to replace mercenary soldiers with peasant militia, arguments justifying the use of the mercenary soldier system were al so prevalent. Supporters of the peasant militia system argued that recruiting peasants as soldiers was a model established by the ancient sage kings, and, thus, the Song government should use this method to solve its military problems During the Shenzong period, Wang Anshi did, in fact, attempt to replace mercenary armies with peasant militias, but his policy aroused a great deal of protest. Wang's opponents insisted that mercenary armies provided protection to commoners and allowed peasants to concentrate on agricultural work and enjoying their daily lives Moreover, separation between peasants and soldiers was of use to the government in maintaining control over society. For these two reasons, Wang's opponents argued, Taizu, the founder of the Song dynasty, had chosen a mercenary system and established this military model for his descendants to follow. The debate between those supporting and opposing mercenary armies constituted a major part of military discourse during the Song dynasty, and created a new military tradition for later rulers who adopted the mercenary system.