Do unto others as you would have them do unto you.
This Golden Rule is attributed to Jesus Christ, but it has also been stated in various ways by other historical leaders. It makes a very good "rule of thumb" for deciding what is good.
Notice that this is also a subjective judgement, because you are deciding based on your own desires how you would like to be treated. The others might have different desires and wishes, however. You can try to compensate for that by guessing what they want, but that is an uncertain process. Therefore it makes sense to think of how you would feel if you were in their shoes.
Some theorists have suggested that one ought to calculate the satisfaction of each person and then optimize the result for society. However, there are practical problems with that. For starters, no person can report an exact score of how happy they are. Even if they could, there is no way to know if one person's report of "100% happy" is truly the same level as another person's "100% happy". Some people might be harder to please. By what formula could one optimize happiness overall? It's fine to theorize that one ought to calculate the result, but no formula has been devised by which to calculate it.
Therefore, we are back to a situation where you make a subjective judgement about what is good, based on how you yourself would feel under various conditions. You might describe this as "subjective ethics." Even though it is subjective, it does not license you to simply do whatever you please without regard to others. You agree to rules based on how you would like to be treated under various conditions, and then you must follow those rules. It is a very practical and simple solution.
From Pathways daily ideas file, copyright Arthur de Leyssac, 2009; all rights reserved.