The fundamental Buddhist morality is summarized in the Dhammapada by Shakamuni in a simple Triplett:
Not to do any evil’
to purify one’s mind.
It is a simple admonition that even a child can understand. But of course we’re not children and so we never tire of trying to muddle things up with analysis. What is good we say, what is bad we say. How can these opposing ideas exist in a non-dualistic mind. The answer is of course they can’t. And the confusing part of this is trying to overlay our Western education on to an eastern idea.
One of the underlying concepts of Buddhism is that we are all deluded. We drift in the world of birth, death, and rebirth propelled by the karma generated by our delusions. I submit to you that delusions are not real and therefore their existence is itself a delusion. On the other hand good or at least those things we call good are called good because they reflect reality. To say we have Buddha nature is to say that we are by nature good, when we fight our true nature we are unhappy and we suffer and cause others to suffer. Fighting your true nature is the result of delusion. All the things we call bad almost universally result in suffering. This suffering is generated by the unreal and untrue nature of the thoughts words and deeds caused by delusion.
Simply put to do good is to conform to reality to do bad to fight reality and come into conflict with it. The result of this conflict is always affliction and suffering. So it is a misunderstanding of the unity of reality to say that good and bad don’t exist. It is evil that doesn’t exist despite its ability to create results which create suffering and harm, it’s underlying nature is delusion. Good has its basic nature firmly seated in reality and thus it is both real and beneficial.
When Buddha first turned the wheel of Dharma he spoke of suffering. The eightfold path is a path away from delusion toward reality toward your true self and your true nature. When you’re in conformity with your true nature and the real world you and those around you suffer less. And that is a very good definition of good.
I know there are Buddhist teachers that are running around teaching complete and total "in action" and "lack of thought" or no mind in order to stop generating karma. This is itself a delusion. Compassion is that emotion which occurs when our love for all sentient beings is confronted by their suffering. The overwhelming desire to end the suffering of others is generated within the bodhi mind. Unless these things occur there can be no awakening and there can be no enlightenment.
If you want to know if an action is good or bad simply follow the advice Buddha gave to his son. Determine if this action will cause you or others to suffer. If it does cause suffering it is not a good thing. When we analyze our thoughts our words and our actions: we need simply consider the following: is this thought speech or action in conformity with that which leads to yourself and others being in a state of:
1. Firm: resolute, stable, unmoving, undistracted.
2. Pure and clean: unstained, immaculate, bright.
3. Clear and free: unrestricted, free, exalted, boundless.
4. Fit for work: pliant, light, fluent, patient.
5. Calm and content: relaxed, serene, satisfied.
Buddhist morality is really very simple, it doesn’t rely on a list of do’s and don’ts, it is not enforced by a vengeful God. It simply reflects the nature of reality.Karma and its fruits are simply words that describe cause-and-effect as it relates to morality. It’s not complex and it’s not hocus-pocus. It is simply a way to suffer less and cause others to suffer less. Sometimes we call this skillful means other times we call it common sense. In any case do as much good as you can as little evil as you can and purify your mind so you can distinguish between the two.