In this post, Helen Beebee & Alex Kaiserman discuss their recent article in the Causation in War Symposium in Journal of Applied Philosophy on how a probabilistic account of causation speaks to civilian immunity in war.

According to orthodox just war theory, combatants in armed conflicts don’t have rights against being intentionally killed. But this position has come under sustained attack from moral theorists in recent years. What grounds permissible killing in war, many argue, is just what grounds permissible killing in ordinary life.

It’s not OK to kill someone out of revenge, or even because they just stole your expensive laptop and that’s the only way to retrieve it; but it is OK to kill them if they pose an immediate and unjustified threat to the life of you or your neighbour or a stranger, and killing them is the only way of averting that threat. Similarly for combatants: the right to life is universal, so if a combatant lacks such a right, it’s not in virtue of being a combatant, but rather in virtue of having forfeited her right by wrongfully contributing to an unjustified lethal threat to another person, thereby rendering her liable to be killed in self- or other-defence.

One consequence of this approach is that not all combatants are equal. If the armed forces of Aggressorland unjustifiably threaten the citizens of Victimland, they may forfeit their rights not to be killed by the armed forces of Victimland. But in threatening to respond in this way, the armed forces of Victimland do not forfeit their rights against being intentionally killed, because the threat they pose is justified. In some ways, then, this revisionist approach to the ethics of war offers more moral protections to agents in armed conflicts than traditional just war theory.

The focus of our paper, however, is on the consequences of such a view for non-combatants. On the face of it, if combatants shouldn’t be stripped of their rights to life simply in virtue of being combatants, then neither should noncombatants be allowed to keep their rights to life simply in virtue of being non-combatants. The civilians of Aggressorland may have wrongfully contributed in all kinds of ways to the unjustified threat to Victimland: by voting for the war, manufacturing arms, providing food and medical assistance, or writing pro-war articles, for example. The revisionist seems forced to concede that these civilians, as well as the combatants they support, are legitimate targets of defensive attack.

Some authors – such as Cécile Fabre, Seth Lazar and Jeff McMahan – have suggested that although many non-combatants do indeed contribute to unjustified threats, their contributions are usually too small, or remote, or insignificant, to make them liable to defensive attack. In other words, it would be morally impermissible to kill them to avert the lethal threat they are contributing to because that contribution is just too insignificant.

Proponents of such a view have typically had a lot less to say about what they mean by ‘causal significance’, however. As such it’s not especially clear whether the view actually has the consequences its proponents take it to have. Is the army medic’s contribution to the threat posed by a soldier by making her fit for armed combat more or less ‘remote’ or ‘significant’ than that of the mechanic in the factory that manufactured the soldier’s ammunition? Does the propaganda writer make a larger or a smaller causal contribution to the threat her country poses than the army private too scared to fire her weapon? We simply lack the resources to answer these questions. This invites the legitimate accusation that just war theorists are simply using the idea of ‘causal contribution’ as a placeholder for whatever will deliver what they have pre-theoretically decided are the correct results – usually, the result that unjust civilians are not liable and unjust combatants are.

What’s needed, then, is an account of degrees of causal contribution that can be applied to these debates in the ethics of war. Such accounts, however, are thin on the ground. In our paper, we sketch a recent probabilistic account – already developed and defended elsewhere by one of us (Kaiserman) – and see whether it allows us to draw the kinds of moral distinctions between combatants and civilians, or between different kinds of civilians, that some just war theorists have tried to defend.

Our conclusions are mostly sceptical, because it turns out that an event’s degree of contribution to the causing of some effect depends very sensitively on extrinsic details of the case, including facts about the other causes involved in bringing the effect about, the presence or absence of potential back-up causes, and other factors besides. Driving munitions to the front line might make a large contribution to a threat in some circumstances and a small contribution in others; the same goes for providing medical care or tightening screws on a tank engine. Hence regardless of whether degrees of causal contribution do make a difference to liability – and we do not commit ourselves either way on this question – they do not allow us to draw any neat moral lines between different kinds of people, or even different kinds of activities, on the unjust side of a war.

The Journal of Applied Philosophy is a unique forum for philosophical research that seeks to make a constructive contribution to problems of practical concern. Open to the expression of diverse viewpoints, it brings the identification, justification, and discussion of values to bear on a broad spectrum of issues in environment, medicine, science, policy, law, politics, economics and education. The journal publishes in all areas of applied philosophy, and posts accessible summaries of its recent articles on Justice Everywhere.