Tooth Fairy Bullshit

[Mister Agenda]

That's some ludicrously obvious bullshit right there.

He's  right though. On what basis do we claim that a particular act is objectively good? Why is it good to help people and bad to hurt people? 

Pointless suffering is bad. If you have an example where it isn't, I'd like to hear it.

I've heard it said that I help other people for the good of our species because it comes back to me and helps keep me alive. Because we each evolved to stay alive by helping out in our communities.

You help other people because you are kind and helpful. People likely treat you better because they know you are kind and helpful. The capacity for at least some of us to be kind and helpful is good for a social species, and evolved in us and to an extent, in other social primates. There are objectively better and worse ways to order a society, by any reasonable criteria. The old thought experiment is 'what would you want to your society to be like if you were introduced into in a random way, not knowing if you would be king, soldier, serf, or slave?'  

But at some point in the future we will get to a place where we are so over populated, that it will be to our personal benefit for other people (unless they are particularly important) to die, not for them to live. Do we eventually evolve to think that hurting people is good and helping them is bad?

That would seem to be an impossible scenario given the time frame (it would take many generations to evolve to be antisocial) and the nonviolent options available for population control; but as a thought experiment, yes, it is conceivable, though extremely unlikely, that we could evolve, say, into a solitary, antisocial species that only gets together to procreate and aggressively defends its territory otherwise. Even species like that have rules, though. Unless you have hundreds of young, it's bad evolutionary policy to kill your own descendants, for instance. It's bad evolutionary policy to get into fights that don't increase your chance to reproduce (fights often have the opposite effect). But your basic point that if we were very different, our morals could be very different is true. I'm not sure how that helps your case for an absolute morality, though. If there were such a thing, surely all creatures would follow it to the extent that they were able? God wouldn't give one set of moral instincts to primates and another to felines if morality were absolute, surely?

My position: morality is objective, but not absolute. We don't need an absolute standard for where 'shortness' ends and 'longness' begins to be able to objectively state which of two strings is the longest. In fact, I can't think of any situation where an absolute standard is required in order to compare two things on any particular quality...but suddenly, when it comes to morality, people with a vested interest in their being such a standard claim you can't 'do morality' without it.