Culpability distribution

Suppose a symmetrical conspiracy in which, doing equal amounts of work with equal amounts of intent-to-kill, a group of $ M $ murderers conspires to murder $ V $ victims. Suppose someone claims that, since each of the murderers contributed only partially to the outcome (but each one contributed an equal share), then each murderer is guilty, not of $ V $ counts of murder, but of $ \frac{V}{M} $ murders. Let’s call this assumption Contribution-Proportional Culpability (CPC).¹

No legal system on Earth accepts Contribution-Proportional Culpability. (To see this, consider that if $ M = V > 1 $, no legal system would charge each murderer with only 1 count of murder.) Instead, all legal systems accept Damage-Proportional Culpability (DPC): each of the $ M $ murderers is culpable for $ V $ counts of murder. We generally accept this “intuitively”—I certainly would blame each murderer for $ V $ murders, without thinking about it. But it’s not obvious why we should accept DPC, rationally speaking—and in face of the argument that “each of the murderers contributed only partially to the outcome”, we may be led to doubt. So what’s the reasoning for DPC?

My current conjecture is that we reason like this: We may grant that each murderer is culpable for $ \frac{V}{M} $ deaths, but the relevant unit of culpability is not “deaths”, but “murders”, or what one may call “culpabilities-for-deaths”. Since each member is necessary to the conspiracy, each murderer is causing all the other murderers to become murderers, and therefore, each murderer is culpable for the crime of all the other murderers as well as for his own. Hence, each murderer is culpable for $ \frac{V}{M} \times M = V $ murders, as required by DPC.

This reasoning, however, may allow for CPC to be followed in a case where $ M > 1 $ murderers are all necessary for a murder to occur, and each one contributes to the murder with intent to kill, but none of them are aware that there are any other contributors. Whether it can do so in practice, is left as an exercise to the reader.

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1. In a post to X, I referred to CPC as “Blame-Sharing”. I avoided this name in this post because the only name for the alternative would be “non-Blame-Sharing”, which isn’t very descriptive since there could be other possible assumptions about blame distribution than the two considered here.↩