 To illustrate, suppose a 100-member firing squad is about to shoot an innocent child. Each bullet will hit the child at the same time, and each shot would, on its own, be sufficient to kill her. You cannot stop them, so the child will die regardless of what you do. Now, suppose they offer you the opportunity to join in and shoot the child with them. You can make the 101st shot. Again, the child will die regardless of what you do. Is it permissible for you join the firing squad? Most people have a strong intuition that it is wrong to join the squad and shoot the child. One plausible explanation of why it is wrong is that there may be a general moral prohibition against participating in these kinds of activities. In these kinds of cases, we should try to keep our hands clean.