Suppose it is foreseeable that you will soon encounter a drowning child, whom you will only be able to rescue if you learn to swim. In this scenario we might think that you have a “prospective duty” to take swimming lessons given that this will be necessary to perform the future rescue. Cécile Fabre argues that, by parity of reasoning, states have a prospective duty to build and maintain military establishments. My argument in this essay pulls in the opposite direction. (...) First, I emphasize that learning to swim is only a prospective duty under very specific circumstances. Normally there is no such duty; hence, we do not normally think that people deserve moral censure for choosing to forego swimming lessons. I then argue that, similarly, while a prospective duty to build a military can arise under some conceivable circumstances, these are not the circumstances that most states today find themselves in. I then suggest a more fitting domestic analogy to guide our thinking about this issue: Maintaining a standing army is less like learning to swim and more like keeping an assault weapon in the home “just in case.” This analogy supports a defeasible presumption against militarization. (shrink)