Assumption: that everyone reading this has a personal morality that makes certain actions “wrong”.
In philosophy, a distinction is made between the justice of war (jus ad bellum) and justice in the way a war is fought (jus in bello). Under the latter category, philosophers have included two broad principles, proportionality and discrimination. Proportionality states that you should only fight with the means necessary to achieve your objective – e.g. destroying (for example) Sarajevo with a nuclear warhead would have been disproportionate for the aim of securing peace in the former Yugoslavia. Discrimination states that you should only target those “involved” in the war, not innocent civilians. A more detailed view of this whole area is available at the Internet Encyclopedia of Philosophy.
There are obvious problems with both principles. How do you define a civilian? What about a munitions worker? Or a freight train driver? How do you define “disproportionate”? Did the attacks on Nagasaki and Hiroshima save the lives of many more Japanese and Americans than they killed?
If you assume that these principles are defensible, and that there are certain ways of fighting a war that are “wrong”, would you still support using them as a deterrent? I’m thinking mainly of the ethics of threatening nuclear war; the threat of dropping warheads on your enemy’s towns and cities.
The question: is a deterrent based on a “wrong” action morally acceptable? Or, do you reject the whole concept of a war being fought by “just” means? Feel free to use any other examples you can think of – I don’t mean this to be restricted to nuclear weapons, or even to war (could capital punishment come in here?).