I think good and bad can defined as two things weather and climate(this is a analogy not the actual words im trying to describe)say we people are weather we come in different types sunny,cloudy,rainy etc... over time we get a norm and everybody expects that norm to happen like how people say that its okay to read hentai as long as it doesn't have lolicon, we'll call this sunny weather and say someone says they like lolicon, we'll call them rainy weather(im not saying anything bad about lolicon i personally like it)but since nobody is you'st to rainy weather they either say its okay which normally doesn't happen or they say its horrible and it should never happen.
The only problem with this is that peoples ideals could change unlike weather which cant change.Sorry if this analogy doesn't help also if you still don't get it here is my straight forward answer i do think moral beliefs is mainly based on society.
Badguy wrote...
Side question:
Is it morally wrong to take the life of one healthy person in order to save the lives of 20 or more sick people?
i know it sounds weird but im going to answer your question with another one, if i kill that one healthy person will the sick people be saved in health or saved in another way because im not going to kill a person just to find out that the people i saved are going to die a week later because there still sick