Are good and bad quantifiable or absolute?

In Fowles book The Magus, Conchis tells a purportedly true story about an event in a Greek village during the Nazi occupation. Partisans from the region and from the village itself had been carrying out guerrilla activities against the Nazis. Nazi troops had then occupied the village, rounded up all the residents and the Mayor, and presented the Mayor with a choice of himself executing ten villagers, all of whom he knew, or if he refused to do so, the Nazis would execute everyone there.

The Nazi officer gave the Mayor a rifle with which to execute his choices of villagers. Of course, the Mayor immediately turned the gun on the Nazi officer and pulled the trigger. The gun was, of course, unloaded, the officer said. You must carry out the executions with the butt of the rifle, he added.

The latter detail doesn't change the ethical shape of the dilemma, of course. It only makes the choice more dramatically unpleasant. It's the choice itself that is of interest. Is it ever morally acceptable to carry out an evil act in order to prevent a greater evil? The dilemma can be rephrased: Are ethics absolute, or are they relative and quantifiable?

The United States has taken both sides of this question, sometimes simultaneously. For instance, we held "war crimes trials" after the second World War. Shortly before this event (or events) we had dropped atomic weapons on Nagasaki and Hiroshima, on the grounds that the horrific deaths of the civilian population could be justified if they caused the Japanese to surrender and thus avoid many more deaths. We firebombed Dresden using the same logic. We excoriated the Germans for bombing London, but used their own tactics against them.

I'm not taking a side here. If I had to, I would probably take an absolutist side. The question is a legitimate one, though. Is it better to kill a few in order to avoid the deaths of many more? Is it acceptable to kill mice in order to save people? Is it morally correct to send men to death in battle in order to protect the majority population? I think it's amazing that when we advocate most loudly for a relativist moral position we are generally among the population that is most benefited by it.

In the choice offered in the story in The Magus, a linguistic trick is played on the reader to make it seem that the Mayor has a terrible choice. The Mayor is told, in effect, that he will be responsible for the deaths that result if he chooses not to take part in the executions. This is not true, of course. The soldiers who follow their orders will be responsible for the outcomes of their action, not the Mayor. If he chooses to try to spare the majority of the villagers by himself killing ten, he is clearly carrying out an unethical (or at least immoral) act. If he doesn't do that, he is not responsible for what the soldiers might or might not do. He will have no way of knowing that the Nazi officer will carry out his part of the "agreement"; he could kill the ten and then the Nazis would do whatever they chose to do.

It seems to me that no matter what conditions are assigned to a choice, the individual who makes the choice carries the responsibility for his own actions, as do those of the others (if any) involved. Such a position of absolute morality doesn't fit well with our more modern and politically astute positions of moral relativity. Something is acceptable if it isn't as bad as the alternative. Really? And are we sure that the alternative is our responsibility too?