The question whether both enemies in a war could claim the same right, was a fundamental topic in the early modern theory of war and Grotius treated it briefly in his On Law of Prize and Booty. The jurisprudence of the seventeenth century developed two explanations: the Scholastic tradition held that only one party could fight with right reason, whereas some authors of the humanistic tradition thought that in some cases it was impossible to solve this question. Grotius took elements from both traditions, applying them to two different levels of his argument. If we namely consider the rulers, we should accept the Scholastic conclusion that only one party can fight with right reason. But the subordinate soldiers do not always have an exhaustive knowledge of the situation and need first of all to acknowledge that their superiors command legitimately. Thus, each level uses a different logical relationship in the Aristotelian square because the enemies follow in the former case the pattern of contrary propositions, but in the latter they obey a pattern of subcontrary propositions.