Terrorism is justified if it eliminates more evil than it causes
The consequentialist theory of ethics argues that whether an act is morally right depends only on the consequences of that act. Classic utilitarianism held "act consequentialism" -the claim that an act is morally right if and only if that act maximizes the good. Under this ethical framework, terrorism is morally right if its consequences bring more good than bad. Terrorism is considered wrong only if it has bad consequences on balance. The innocence of the victims does not change that. Historical evidence shows that terrorism employed in conjunction with guerilla warfare in a war of liberation can well prove useful as it did in Algeria and South Vietnam. In these cases, terrorism can be justified since it served as an effective tactic to drive out an oppressor. Some consequentialists emphasize that terrorists tend not to take the need for moral justification seriously enough and that it is very difficult to satisfy the requirements of its consequentialist justification. One must show that the desired objective, when it is eventually achieved, will indeed be so valuable as to justify all that the terrorist does on the way of achieving it. Additionally, the objective needs to be not possibly achieved by other, less problematic methods. Overall, terrorism is justified if the benefits of its consequences are greater than its costs during the process.
One problem of the argument is that the “higher good” promoted by terrorism is more often than not defined in ideological terms rather than from settled preferences or interests of actual people. For example, if the result of terrorism is the administration of Islamic law in a country, those with an Islamic ideology would consider the consequence as good contrary to others who would deem this consequence as bad because it restricts the freedom and liberty of people. Additionally, consequentialism requires the treatment of victims as objects to be used by terrorists. As Arthur Koestler once wrote, “twice two are not four when the mathematical units are human beings.” The arithmetic calculation of net benefits by consequentialists disregards this fact. Every human being is an individual, a person separate from other persons with a unique value that is not commensurable with anything else. In this sense, terrorism is never justified.