What do we mean when we say that someone is responsible for something? This question is remarkably hard to answer. Or better, it does not have one correct answer. Sometimes, by saying that some agent i is responsible for some state-of-affairs φ, we mean to express that it would be appropriate to blame or praise agent i for φ being the case (depending on whether φ is desirable or not); sometimes we, however, mean to say that i should bring about φ, or at least do everything in i’s power to bring about φ. We also might also intend to say that i is to account for φ being the case (or not being the case), or-if the occurrence of φ has caused damage to another agent j, is to pay damages to j.