 Both the “supreme emergency” and the “moral disaster” view will justify a resort to terrorism only when that is the only way to deal with the emergency, or to prevent the disaster, respectively. Just how certain must we be that terrorism will indeed achieve the goal, while no other method will? One might argue that when in extremis, we cannot apply stringent epistemic standards in deciding how to cope—indeed, if we cannot really know what will work, we must take our chances with what might. This is Walzer’s view: in such a predicament, we must “wager” the crime of terrorism against the evil that is otherwise in store for us. “There is no option; the risk otherwise is too great” (Walzer 2000: 259–260). It may be objected that this position highlights the enormity of the threat, while failing to give due weight to the enormity of the means proposed for fending off the threat—the enormity of terrorism, of deliberately killing and maiming innocent people. When that is taken into account, the conclusion may rather be that even in extremis, if terrorism is to be justified, the reasons for believing that it will work and that nothing else will must be very strong indeed.