What is the exact criteria for determining good and bad ( moral ) in Buddhism ?
Itâs probably not what you meant, but the most precise answer is I would say: Whatever brings you closer to sambodhi/enlightenment is âgoodâ - what keeps you away from it is âbadâ. Sambodhi is after all the beginning and end of the teaching. Everything else, even âethicsâ is subordinated.
The more traditional answer is that right behavior, right speech and right intentions (as defined in the Eightfold Path) are the center piece (but not all) of Buddhist ethics.
Or even more simply: Harming yourself and/or others is âbadâ, not-harming yourself and/or others is âgoodâ.
Good description! For me, I think it could also be described as:
Increasing suffering for yourself and/or others is âbadâ. Decreasing suffering for yourself and/or others is âgoodâ. Doing neither is âneither bad nor goodâ.
One might think of MN 61 as giving criteria; excerpt with some added formatting:
[The Buddha:] What do you think, RÄhula? What is the purpose of a mirror?â
âItâs for reflection, sir.â
âIn the same way, deeds of body, speech, and mind should be done only after repeated reflection. When you want to act with the body, you should reflect on that same deed:
[Criteria:]
âDoes this act with the body that I want to do lead to hurting myself, hurting others, or hurting both? Is it unskillful, with suffering as its outcome and result?â If, while reflecting in this way, you know: âThis act with the body that I want to do leads to hurting myself, hurting others, or hurting both. Itâs unskillful, with suffering as its outcome and result.â To the best of your ability, RÄhula, you should not do such a deed. But if, while reflecting in this way, you know: âThis act with the body that I want to do doesnât lead to hurting myself, hurting others, or hurting both. Itâs skillful, with happiness as its outcome and result.â Then, RÄhula, you should do such a deed.[Same criteria for deeds of speech and mind]
At the end of the sutta we see:
All the ascetics and brahmins of the past, future, and present who purify their physical, verbal, and mental actions do so after repeated reflection. So RÄhula, you should train yourself like this: âI will purify my physical, verbal, and mental actions after repeated reflection.ââ
In MN 19 (Two Kinds of Thought) the Buddha gives a detailed description of how to use these criteria in meditation (excerpt with some added formatting)
Then, as I meditatedâdiligent, keen, and resoluteâa sensual thought arose ⌠a malicious thought arose ⌠a cruel thought arose. I understood: âThis cruel thought has arisen in me. It leads to hurting myself, hurting others, and hurting both. It blocks wisdom, itâs on the side of anguish, and it doesnât lead to extinguishment.â
When I reflected that it leads to hurting myself, it went away. When I reflected that it leads to hurting others, it went away. When I reflected that it leads to hurting both, it went away. When I reflected that it blocks wisdom, itâs on the side of anguish, and it doesnât lead to extinguishment, it went away. So I gave up, got rid of, and eliminated any cruel thoughts that arose.