No one knows for sure what is right or wrong. Because no one knows for sure, we should refrain from imposing our personal values on anyone else. Several people in class thought that relativism was a silly theory, because according to relativism if a society believed that torturing small animals for pleasure was morally right their belief would make it morally right. Others in the class were willing to stick to relativism even with its sometimes unintuitive consequence. We then discussed a particular example of a moral realist theory - Utilitarianism.
Utilitarians propose the following criterion for morally right actions.
The right action to do in a particular circumstance is the action that would bring about the most benefit. Utilitarianism is a very intuitive theory. We often say that an action is morally wrong because it would cause a lot of pain, or that an action is morally right because it would benefit a lot of people. Everyone's interests are included not just the agent's interests. According to Utilitarianism everyone's interests weigh equally.