On the subject of morality, most people tell me that they think morals are totally or partially objective. In other words, they say that there are intrinsically good and bad actions that you can do, and that doing good things makes you a good person, and that doing bad things makes you a bad person. For example, you might think that murdering your fellow, law-abiding countrymen is a bad deed objectively. Almost everyone outside of an insane asylum would agree that you shouldn't do that.
The problem of this becomes apparent when you imagine them from a non-human, scientific perspective. Whether you kill people or not makes no difference to the rocks, or the air, or the stars. The only thing that the morals could matter to are humans, and possibly other sentient life forms if we ever met one. The only evidence for the objectivity of morals is the fact that almost everyone agrees on certain ones. But this is argumentum ad populum and is not real evidence at all.
The truth is, morality is purely man-made and relative to each person. Morals are no different than any other meme that we have created. If someone disagrees that it is wrong to kill other people, it is not because he is insane, it's because he is only different. Different memes make up his mind.
There are several reasons why so many people have similar morality. First of all, it is passed down from your parents and is deeply ingrained in your mind. This is going to be very difficult to change, especially because it is rare that people question these seemingly objective morals. There is also the fact that you are severely punished for acting contrarily to the moral standards. You can go to jail for a very long time if you do something "bad" enough.
Morals are not a bad thing for the survival of our race due to their subjectivity. They are actually quite good. The reason that the moral "you should not kill other people" exists is for the preservation of our race. If people just randomly killed each other because they felt like it, there probably wouldn't be very many humans left. If someone's personal goal did not include the preservation of our race, then he might just start killing people. Luckily though, we can easily stop him before he kills too many.
Let me know what you think about this below.