In discussions of moral responsibility for collectively produced effects, it is not uncommon to assume that we have to abandon the view that causal involvement is a necessary condition for individual co-responsibility. In general, considerations of cases where there is “a mismatch between the wrong a group commits and the apparent causal contributions for which we can hold individuals responsible” motivate this move. According to Brian Lawson, “solving this problem requires an approach that deemphasizes the importance of causal contributions”. Christopher (...) Kutz’s theory of complicitious accountability in Complicity from 2000 is probably the most well-known approach of that kind. Standard examples are supposed to illustrate mismatches of three different kinds: an agent may be morally co-responsible for an event to a high degree even if her causal contribution to that event is a) very small, b) imperceptible, or c) non-existent (in overdetermination cases). From such examples, Kutz and others conclude that principles of complicitious accountability cannot include a condition of causal involvement. In the present paper, I defend the causal involvement condition for co-responsibility. These are my lines of argument: First, overdetermination cases can be accommodated within a theory of coresponsibility without giving up the causality condition. Kutz and others oversimplify the relation between counterfactual dependence and causation, and they overlook the possibility that causal relations other than marginal contribution could be morally relevant. Second, harmful effects are sometimes overdetermined by non-collective sets of acts. Over-farming, or the greenhouse effect, might be cases of that kind. In such cases, there need not be any formal organization, any unifying intentions, or any other noncausal criterion of membership available. If we give up the causal condition for coresponsibility it will be impossible to delimit the morally relevant set of acts related to those harms. Since we sometimes find it fair to blame people for such harms, we must question the argument from overdetermination. Third, although problems about imperceptible effects or aggregation of very small effects are morally important, e.g. when we consider degrees of blameworthiness or epistemic limitations in reasoning about how to assign responsibility for specific harms, they are irrelevant to the issue of whether causal involvement is necessary for complicity. Fourth, the costs of rejecting the causality condition for complicity are high. Causation is an explicit and essential element in most doctrines of legal liability and it is central in common sense views of moral responsibility. Giving up this condition could have radical and unwanted consequences for legal security and predictability. However, it is not only for pragmatic reasons and because it is a default position that we should require stronger arguments (than conflicting intuitions about “mismatches”) before giving up the causality condition. An essential element in holding someone to account for an event is the assumption that her actions and intentions are part of the explanation of why that event occurred. If we give up that element, it is difficult to see which important function responsibility assignments could have. (shrink)