 These all matter to the ethics of war, and will be addressed below. However, it is unhelpful to view them as a checklist of necessary and sufficient conditions. When they are properly understood, only proportionality and necessity (in the guise of last resort in the jus ad bellum) are necessary conditions for a war, or an act in a war, to be permissible, since no matter how badly going to war fails the other ad bellum criteria (for example) it might still be permissible because it is the least awful of one’s alternatives, and so satisfies the necessity and proportionality constraints.