The loser in the lottery is the sacrifice, the scapegoat. Tradition and mob psychology carry everyone along. The injustice is palpable. Yet no one person’s contributions are causally responsible for the death of the victim. Who is to blame? The community blindly sustains the tradition, but perhaps they did not originate it. The children pile up stones. The adults throw them. The contributions of the adults will not all be equal. Some may throw larger stones or throw them harder. Some stones hit in more vulnerable places. We want to say that they share the blame, but what portion is to be assigned to each person who participates? 

An initially appealing answer is that each is responsible in proportion to their causal contributions. In Jackson’s story the village has about 300 members. For simplicity, suppose we divide the blame equally among them. The puzzle is this: then it seems no one is responsible for the murder of the victim. 1/300^th of the blame for a death is not the whole blame. If the degree of blame responsibility decreases with the number of participants, then we have a strategy for reducing it to next to nothing. If you do not want to be guilty of murder, you can recruit someone to help. To further reduce the burden, recruit additional helpers. You want to kill your rival. Recruit a million people to help by each dropping a grain of sand into a pit into which he has fallen. With a million participants, no one would be to blame to any significant degree at all. But how can the injustice disappear like this when we move from the group to its members? 

The logic of proportional responsibility is inexorable. The actual crime disappears when responsibility is shared in proportion to causal contribution. The radical solution is to say that responsibility is not diluted simply by being shared. Take the case of two people who work together to kill someone. Each intends the victim’s death. They both make their contributions in coordination with the other, counting on the other for the effectiveness of their own. Each intends, given the other’s contribution, his to suffice for the death. Abstract from the fact that what each counts on is another agent’s contribution. Treat that as part of the causal background. Then it is no different from relying on, for example, the mechanism of a gun when pulling the trigger, or the presence of gravity when pushing someone off a cliff. We then have the same grounds for holding each fully responsible as we do when they act alone. The logic of this position is also inexorable. Each person who casts a stone is equally and fully responsible for the murder of the victim. And if a million people knowingly act together in a way that causes a death, or another harm, even if it is by dropping a single grain of sand, they are each equally and fully morally responsible for it. Each is guilty of murder. For otherwise the crime disappears from accounting.

Many collective crimes are overdetermined. Suppose that if even half of the villagers threw stones, the victim would still have been killed. Then the contributions of none of them are necessary for the death. If any one of them had not participated, the victim would still have died. Surely if it would have happened anyway, you cannot be blamed for it. But if this were correct, then since it is true of everyone who participated, no one would be to blame to any degree. And to ensure that you were not to blame for any crime, it would suffice to recruit one more than was necessary for it to come about. If two assassins agree to shoot their victim at the same time, it does not relieve them of individual responsibility for the death that it would have occurred if either alone had not acted. Each is still a contributor to the causal stream that results in the harm. The actions of each constitutes part of the total cause. Overdetermination then relieves no one of full and equal responsibility for participation.

The implications of this position are daunting. We are collectively morally responsible for anthropogenic climate change, and we are collectively morally responsible for doing something about it. No one individual is responsible because changing the world’s climate is far beyond the power of any individual. Nor could any one individual’s withdrawing from activities that contribute to climate change make a difference. Our activities massively overdetermine global warming. But if what we said above is right, this is not a responsibility shelter. The harms from global warming, while difficult to trace, are massive, and will increase as time goes on. This burden seems too huge to bear. We are like the villagers in Jackson’s story in that we are born into arrangements that lead us to participate in (in our case massive) harms. The question facing them and us is how to respond. One moral seems clear: doing nothing is indefensible, and since individual action is insufficient, we must contribute to collective action in responding to harms that arise from collective action. Where there are preexisting organizations (such as governments) in whose purview relevant action lies, we must influence them to take appropriate action; where there are not, we have a duty to collectivize to respond. Traditional moral theory focuses on individual action, but the greatest harms and the greatest goods arise from what we do together.