Relativity of ethics
Relativity of ethics is the concept that something that is deemed good might not be good for everyone.
The word good is a relative term. From an observer's perspective good can be entirely dependent on its framing. However, for people who want to do good how can this be determined? For instance, on the Death Star, Luke and the Rebels went out to blow it up but, what of the Imperial officer coming to work to feed his newborn baby? Was Luke doing good when he launched the proton torpedo blowing them all up or was the Imperial officer doing bad when coming to work to feed his child? The only 100% good, would be what is in the common good for all. Its arguable that Luke was the one doing good as even though the Imperial Officers loss of life was tragic, in the long run the galaxy would be better of in the absence of an oppressive state.
The Definition of Good
In this galaxy, not so far away.. under your feet in fact, we all stand on the earth. We all drink the same water, breathe the same air, if someone truly thought their aim was to do good, their actions would primarily be involved in protecting the earth as this is common to us all. Once looking from this perspective one can start to see the real bad and good actors.