Rationality is at the core of the human mind. Rational decisions lead to better outcomes and thereby increase the chances of winning a war. Despite divergent definitions, rational behavior is usually postulated as soon as a person (or nation or agent) has selected the best actions to achieve goals. This definition is purely instrumental and thereby mute with respect to the agent’s goals. The goal of subduing a peaceful nation, for example, may be morally condemnable or not. But this moral judgment is irrelevant for judging whether the attack was rational, that is, whether the best actions were chosen to subjugate the nation.

Although plausible, this view is too simplistic, because goals can be final or instrumental, and only final goals—unlike instrumental goals—escape rationality considerations. Maximizing ...