Within Mohist thought, war is approached through the lens of universal love (*jian ai*) and the imperative to benefit all under heaven. Offensive warfare—campaigns of conquest, expansion, prestige, or revenge—is condemned as a grave moral failing. Such aggression is likened to large‑scale robbery or murder: if harming a single innocent person is wrong, then orchestrating the deaths of thousands is even more egregious. War is also criticized for squandering resources and diverting energy away from productive activities that could nourish and stabilize society. In this way, aggressive violence is seen as fundamentally incompatible with the demand to care impartially for others.

This ethical stance is reinforced by a kind of utilitarian reasoning: actions are judged by whether they increase benefit and reduce harm. Large‑scale violence predictably brings death, famine, economic ruin, and social disorder, and thus fails the Mohist test of promoting overall welfare. A ruler who initiates such wars is regarded as lacking merit and failing in responsibility to the people, and so is unworthy of true authority. Offensive war is also portrayed as violating the moral order upheld by Heaven, which is understood to desire mutual benefit rather than mutual harm. In this framework, there is no cosmic or ethical legitimacy for aggressive campaigns.

Yet Mohism does not advocate absolute pacifism. Defensive warfare is treated as both permissible and, at times, necessary when it serves to protect the innocent and prevent greater harm. Violence in self‑defense, or in the impartial enforcement of law, can be justified when it clearly minimizes total suffering. Mohist thinkers became renowned for their expertise in defensive fortifications, siege resistance, and military engineering, and they actively assisted besieged cities. This practical engagement with military defense is interpreted as an expression of universal love: a willingness to use limited force so that many more might be spared.

At the heart of this view lies an acknowledged tension between the ideal of universal love and the harsh realities of conflict. Mohism resolves this not by denying the tragedy of violence, but by insisting that any resort to force be strictly constrained by the aim of protecting people and reducing harm. Offensive war stands as a paradigmatic violation of that aim, while carefully delimited defensive action is treated as a reluctant but sometimes necessary means of safeguarding the vulnerable. In this way, Mohist teaching invites a disciplined discernment: to reject violence that serves ambition and greed, and to tolerate only that force which truly embodies care for all.