Argument: Prospect of Success

The war must have a reasonable chance of success. War always involves a loss of life, but expending life with no possibility of achieving a goal is unacceptable. Thus, if a fighting force cannot achieve its goal, however just, it should not proceed. Charging an enemy’s cannons on horseback or throwing troops at a pointless occupation are clearly not just actions.

Candidate 1: "Many nations wage war without official declaration (e.g. the USA’s involvement in Vietnam) and act unilaterally instead. Such unilateralism does not necessarily lead to an inevitable circumvention of the Geneva Conventions, it merely avoids the bureaucracy necessary to draw authoritative approval. Moreover, who is to decide which entities can and cannot issue calls to arms? Legitimate authorities have sanctioned some of the most horrific wars in history."
Candidate 2: "Reality is a lot murkier than theory. How are we to determine a state’s intent? Sometimes good intentions are bound up with bad; public justifications for war may not always represent the real reasons. And who is determine if a peace is just or a wrong has been committed? The nation initiating the war will use its own values to justify its intentions, and these values may be at odds with those of the other party to the conflict. Furthermore, it is altogether possible to fight a war for selfish motives and nevertheless protect civilians and reduce suffering in so doing."
Candidate 3: "Sometimes it is morally imperative to fight against overwhelming odds, as resistance fighters did in World War II. Also this condition may give large nations free rein to bully small ones because they could not win a war. It also may cause a country to surrender in a war it might actually win. Weak countries have won wars against powerful ones – look at the American Revolution. Finally, the point at which a war became unwinnable, and therefore unjust by this definition, is often only identifiable with hindsight – consider the Soviet occupation of Afghanistan, or the American involvement in Vietnam."
Candidate 4: "Sometimes going to war before all alternatives are exhausted is the most moral action. For example, a nation might decide to go to war if it determines that waiting would enable to the enemy to increase its strength and to do much more damage than an early war would have inflicted. This, after all, is the bitter lesson of the failure of appeasement in the 1930s. Waiting might allow an invading state to entrench itself so that far greater force would be necessary to remove it at a later date."
Candidate 5: "We have seen that a proportional response frequently doesn’t work. Suicide bombers continue to blow up victims in the Middle East despite the response. Why should a nation tolerate continued aggression for the sake of proportionality? And if a nation knows it is likely to be attacked, why should it wait to disarm the aggressor? Is not pre-emptive action justified to prevent the loss of innocent life? Finally, what of deterrence: a vigorous response to an aggressive act may not be strictly proportionate, but by making all potential aggressors think twice about future actions, it can be justified as saving more suffering in the long run."
Candidate 6: "Just cause is an elastic concept. Who determines what is “aggression”? Could violating a disputed border region (e.g. Ethopia-Eritrea, Pakistan-India) or imposing economic sanctions (e.g on North Korea) be aggression? And if a state is unable to defend itself, can another state intervene militarily on its behalf? These borderline cases make invoking this criterion very problematic."

Sometimes it is morally imperative to fight against overwhelming odds, as resistance fighters did in World War II. Also this condition may give large nations free rein to bully small ones because they could not win a war. It also may cause a country to surrender in a war it might actually win. Weak countries have won wars against powerful ones – look at the American Revolution. Finally, the point at which a war became unwinnable, and therefore unjust by this definition, is often only identifiable with hindsight – consider the Soviet occupation of Afghanistan, or the American involvement in Vietnam.
