Disclaimer. Don't rely on these old notes in lieu of reading the literature, but they can jog your memory. As a grad student long ago, my peers and I collaborated to write and exchange summaries of political science research. I posted them to a wiki-style website. "Wikisum" is now dead but archived here. I cannot vouch for these notes' accuracy, nor can I say who wrote them.
Wright. 1985. Causation in tort law. California Law Review 73:1735.
The traditional legal model of "but-for" causation (necessary condition causation), while fundamental to the idea of causation in general, is insufficient to account for causation in overdetermined causation cases. Therefore, the NESS test [necessary element of a sufficient set] is needed in these overdetermined cases, which comprise preemptive causation and duplicative causation situations. The key idea here is that one's action can be a contributing causal condition, even if the "but for" test is not met.
It seems to me that efforts to modify the "but for" test to handle the overdetermined causation problem are motivated by our concern for the moral culpability of actors whom the technical application of the "but for" test would absolve. This relates to the Goldman (2002) piece because we seem to instinctively think that even if this person was not the "but for" cause, he is still somehow morally responsible for what happened. As Wright puts it, the courts feel compelled to depart from the "but for" test in overdetermined causation cases because, although the but-for test is not satisfied, "it is clear that the defendant's tortious conduct contributed to the injury." (1792) (emphasis added). In other words, we know that the defendant "had something to do with" the plaintiff's injury.
The pollution example is probably the best analogy to voting. However, one should note that this is an expansion of the overdetermined causation idea (because each factor alone is not sufficient in and of itself to cause the injury) and that this expansion is a direct result of the application of the NESS test.
In the pollution example, we are told to assume that 5 units of pollution were necessary and sufficient for the injury and that each of 7 defendants discharged one unit of pollution. Wright points out that while each defendant can truthfully say that its one unit was neither necessary nor independently sufficient for the injury, each defendant's one unit was necessary for the sufficiency of a set of actual antecedent conditions that included only four of the other units, and the sufficiency of this particular set of actual antecedent conditions was not affected by the existence of two additional duplicative units. If we apply this rationale to voting, we see the following: Candidate A needs 51 votes out of 100 to win, yet 70 people vote for candidate A. While each voter can say that her one vote was neither necessary nor independently sufficient for the victory of candidate A, each nonetheless knows that her vote contributed to causing the victory.
What does Wright's preemptive causation story tell us, if anything, about the problem of the West Coast voter in Presidential elections? Goldman states in his article that national elections featuring different time zones and/or different poll-closing times are "flawed executions of the traditional conceptualization of elections." (278). However, what is the causation story here? Are West Coast voters' votes causally preempted if it is clear that one candidate already has won enough votes in the electoral college? Is it correct to say, in that case, that West Coast voters cannot contribute causally to the outcome because the outcome already has been determined?
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