It seems pretty clear that we have strong, though perhaps at times defeasible, reason to avoid cooperating in evil activities. Here is something, however, that has struck me, after thinking about material in Wojtyla's The Acting Person (he is explicit about the tension) and correspondence with Mark Murphy. There is a tension between this presumption against cooperating in evil activities and the apparent fact that there is a non-instrumental value in all genuine interpersonal cooperation. There are ways to reduce or remove the tension, but it strikes me as quite an interesting tension. Does the fact that an instance of cooperation is in a bad activity somehow subvert the goods of cooperation?