Mobs are often thought to be the last groups that we should be tying to hold collectively responsible. For, they completely lack decision-making procedures, their members are seemingly not related, and they are often chaotic and irrational. But, Larry May (1987), Raimo Tuomela (1989), and others argue, we can nevertheless hold mobs collectively responsible if at least some of their members contribute directly to harm and others either facilitate these contributions or fail to prevent them. For,