You might wonder why those are the things people say when you ask them where morality comes from. There must be a reason why they give those particular answers. Consider the list again:
Pain and pleasure
For the most part, the things on that list are things that all people share, which is why they are good candidates for the source of morality. If you are going to make moral judgments, they should probably be based on something that people have in common. After all, what’s morally right for you should be morally right for anyone else too.
To help illustrate the point, think about this: why do you care about morality at all? Why does it matter? It seems like one likely explanation is that you care about people. But why would you care about them?
It’s probably because you recognize that they are like you. You can imagine how it would feel when good or bad things happen to them, when they are harmed or benefited, because they are like you in important ways. In a sort of roundabout way, you care about people because you care about yourself. You see yourself in others, the way they have feelings and rights and rationality just like you do. So morality comes from whatever things we all have in common. It’s just a matter of which aspects you think are most significant, and which can most reasonably be used to make moral judgments.
Right away, you might dismiss some of these options, and gravitate toward others, but in order to figure out which one is the most reasonable to believe is going to depend on how well the view works as a reliable system for determining what’s right and wrong. Will it give the same answer for everybody? Will it give a clear answer in every case? Can you recommend it to everyone? These are the things we’ll consider when evaluating each option.