Collective harm cases are situations in which things will become worse if enough acts of a certain kind are performed but no single act of the relevant kind will make a difference to the outcome. The inefficacy argument says that since one such act does not make a difference to the outcome, you have no outcome-related reason to refrain from acting in this way. If this argument holds, you have no climate-change-related reason to refrain from going for a drive in a fossil fuel powered car, and no harm-to-the-victim-related reason to refrain from flipping the switch in Derek Parfit’s (1984) famous case of the harmless torturers. There are two ways in which you could understand the inefficacy argument. Either, it says that you lack a reason to ...