Degrees of Causal Contribution and the Ethics of War
Conversations on War is an event organised by Helen Frowe (Stockholm Centre for the Ethics of War and Peace) and Massimo Renzo (King’s College London). The last event was on the theme of Complicity and Causation in War, bringing together experts from metaphysics, moral philosophy and legal philosophy. In this post, Carolina Sartorio (University of Arizona), one of the participants of the last event, presents some problems for the notion of “causal contribution” often appealed in the ethics of war and peace.
Does a person’s liability to be harmed during a war depend on the nature of their causal contribution to the (unjust) threat posed? If so, how?*
The recent literature on the ethics of war has become increasingly focused on questions of this kind. According to some views on these matters, your liability hinges on the extent of your causal contribution: other things being equal, the larger your contribution to an unjust threat, the larger the amount of harm that we can permissibly impose on you in order to avert the threat. Some philosophers have suggested that we can ground a quite general principle of civilian immunity on this basis. At least typically, they claim, the causal contributions that civilians make to unjust threats are too minimal for them to be liable to harm. In contrast, the contributions made by combatants tend to be more significant, and thus combatants tend to be more liable. In general, on these views, contributing more or contributing less to an unjust threat can make you more or less liable to harm; your liability crucially depends on the extent of your causal contribution.
The idea that causal contributions come in degrees is certainly intuitive, and we see expressions of it in ordinary life all the time. When my family and I put together a meal to have for dinner, it’s natural to regard some contributions as more substantial than others. Although I want my young son to feel like he’s made a contribution to our stew by having added the salt, his contribution seems less substantial than if he had chopped the veggies and combined all the major ingredients in our crockpot, instead of just adding the salt.
But, do causal contributions really come in degrees? Can we make sense of a graded notion of causal contribution (one that can be relevant to debates about liability in war)? I think there is good reason to be skeptical. I believe that, at the end of the day, the appearance that causal contributions come in degrees is just an illusion. If so, views of liability that appeal to a graded notion of causal contribution in order to ground principles such as the civilian immunity claim should look elsewhere to ground those principles, or abandon them.
Let’s start by considering the question: If there were degrees of causal contribution, how could one measure such degrees?
One possibility would be to use a “sufficiency” scale: one that measured, roughly, how close a cause came to providing a sufficient condition for the effect. Combining the major ingredients for the stew seems to bring us “closer” to our goal of making the stew than just throwing in the salt. In this sense, combining the major ingredients seems to be more of a contributor, in that it is closer to a sufficient condition for the stew than adding the salt.
Another possibility would be to use a “necessity” scale: one that measured, roughly, how close a cause came to providing a necessary condition for the effect. Again, combining the major ingredients seems to fare better in this respect. We can’t have a stew without the major ingredients, but we can have a stew (although one that isn’t as tasty) without the salt. So, in this sense too, combining the major ingredients seems to be more of a contributor than adding the salt.
The idea that causal contributions come in degrees is certainly intuitive, and we see expressions of it in ordinary life all the time.
This is all at a very rough and intuitive level. But focusing on these two possible scales in just this intuitive manner is enough to see how problems immediately arise for the view that causal contributions come in degrees. In the example of the family dinner that I was imagining, the sufficiency and necessity criteria coincide, in that combining the major ingredients is both closer to a sufficient condition and to a necessary condition than adding the salt. But it needn’t be this way.
Imagine that Grandma’s stew uses a secret ingredient, say, a special type of spice without which it just wouldn’t be Grandma’s stew. Imagine that the other ingredients are not similarly essential to the stew (they are replaceable by other ingredients: the veggies are replaceable by other kinds of veggies, the meat by other kinds of meat, etc.). Under those conditions, adding the spice is a necessary condition for making Grandma’s stew, but it’s still very far from a sufficient condition. So imagine that Grandma put some veggies and meat together, and then her grandson added the special spice at the end. Who made a more significant contribution in this case: Grandma or her grandson?
In this scenario, the sufficiency and necessity criteria seem to pull in opposite directions. The sufficiency criterion points to Grandma, since she provided most of the ingredients and thus, something closer to a sufficient condition for the stew. But the necessity criterion points to her grandson, since he provided the only essential ingredient, and thus a necessary condition for the stew. So, who made the more substantial contribution in this case? Which scale should we use? I feel like I’m at a loss about how to answer these questions.
A similar puzzle arises for the ethics of war. Compare, for example, two technicians who make contributions to an unjust threat by repairing tanks. The first technician regularly does a large number of large repairs, but they are repairs that other members of his unit could have easily done. The second technician does only a small number of small repairs (say, he fixes bolts when they snap), but he is the only one who knows how to do those repairs in his unit. Who makes a more significant contribution to the unjust threat, the first or the second technician? Again, in this case, the sufficiency and necessity criteria seem to pull in opposite directions: the sufficiency criterion points to the first technician, but the necessity criterion points to the second technician.
So, which criterion should we trust? How should we decide this issue? When we ask questions like these I start to lose track of what we’re asking; in fact, the questions don’t seem to make much sense anymore. How could we possibly determine which technician makes more of a contribution? My inclination is to just say that both technicians made acontribution: the first technician made a certain kind of contribution, and the second technician made a different kind of contribution. That’s it. It doesn’t make sense to ask which contribution is larger or more significant. Causal contributions don’t really come in degrees.
For what it’s worth, this is more in line with how metaphysicians tend to think about the causal relation. On most contemporary views about causation, causation is “all or nothing”: an event is either a cause of another event or it isn’t; there aren’t degrees of causation or of causal contribution. Causing an outcome, on most views, is roughly just a matter of “joining forces” with other events or circumstances to collectively bring about the outcome. That’s all there is to it. There are no more significant and less significant ways of making a contribution, just different ways of making a contribution arising from the various ways in which different events can be combined to collectively bring about an effect. Thus, contributing the salt or contributing other ingredients are both different possible ways of contributing to a stew. And fixing bolts in tanks, making other kinds of repairs, or civilian contributions such as donations to a war fund are all different possible ways of contributing to an unjust cause. But none of them make a more substantial contribution than the others.
Now, if causal contributions don’t really come in degrees, then why did it seem so plausible to think that they do? Can we explain the illusion of causal contributions coming in degrees in the same way we may be able to explain, say, an optical illusion?
I suspect so, at least for the most part. One possibility is that, in judging that causal contributions come in degrees, we are conflating what philosophers call “token causation” and what they call “type causation.” For example, “Smoking causes lung cancer” is a type-causation claim: it says that events of a certain type tend to cause events of another type. To say that smoking causes lung cancer is not to say of any particular (“token”) smoking event that it causes lung cancer, but it is to say, roughly, that smoking events often result in cancer. There are also comparative type-causation claims, such as “Smoking twenty cigarettes a day causes more lung cancer than smoking only one cigarette a day.” Again, these aren’t claims about particular causal contributions, but they report that events of a certain kind result in cancer more often than events of another kind.
So consider, for example, the claim that cooking some veggies and meat in a crockpot contributes more to the making of a stew than just throwing in the salt. Understood as a type-causation claim, all it says is that cooking the veggies and meat tends to result in a stew more often than just throwing in the salt. In other words, cooking the veggies and meat has more of a (general) power to result in a stew than just throwing in the salt. This is of course true, but it’s perfectly consistent with actual causal contributions not coming in degrees at all. So perhaps, in cases like this, when we judge that some causal contributions are larger than others, we are conflating type-causation claims and token-causation claims, or general powers with actual causal contributions. Although this is a confusion, it is perhaps an understandable one.
Causing an outcome, on most views, is roughly just a matter of “joining forces” with other events or circumstances to collectively bring about the outcome.
Happily for my son, then, on reflection I think we should say that, when I put together the major ingredients for the stew and he added the salt, we both “equally” contributed to the meal. Although I did something that has the general power to result in a stew more often than what my son did, this is not something that reflects on our actual contributions. We both actually contributed (although in different ways) to the making of the stew, and neither contribution was larger or more significant than the other.
Interestingly, however, at the same time this opens the door to other ways in which one could try to make discriminations about liability in the ethics of war, aside from appealing to the extent of one’s causal contribution. Imagine that you do something that you know tends to result in an unjust threat more often than other behaviors. Then we could plausibly hold you liable (or more liable than other agents) on those grounds. But notice that in that case what would make you liable (or more liable than other agents) is not the extent of your actual causal contribution. Rather, it’s the fact that you are knowingly engaging in behaviors that have a significant potential of contributing to an unjust threat.
In conclusion, I have suggested that we shouldn’t conceive of causal contributions as coming in degrees. If I’m right, this can have important implications for the ethics of war and, in particular, for how we should think about the relation between liability and causation. Even if you’re not convinced, this much remains true: philosophical debates about liability in war would benefit from a more in-depth examination of the concept of causal contribution and its alleged ties to liability.
* I develop the ideas of this post in more detail in my paper “More of a Cause?” (forthcoming in an issue on causation and war edited by Helen Frowe and Massimo Renzo).
 See, e.g., Cecile Fabre, “Guns, Food, and Liability to Attack in War” (Ethics, 2009), and Jeff McMahan, Killing in War (Oxford University Press, 2009).
 On this point see also Sara Bernstein, “Causal Proportions and Moral Responsibility” (in Shoemaker, ed., Oxford Studies in Agency and Responsibility, Oxford University Press, 2017).
 An exception is David Lewis’s later “influence” account of causation (“Causation as Influence,” Journal of Philosophy, 2000).
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