What IS good, and how do we determine it?

[Mister Agenda]

Do you realize you couldn't even get consensus on your"murder is universally wrong" proposition?  This alone should be showing you that there simply are no universal morals.

Killing other humans is often considered wrong, but there are always situations where it is also acceptable.  Even, sometimes, what we would call murder.

Take the common college class example.  There is a train coming, and the track divides nearby. On track A you see 10 people are tied to the tracks, and this is the track the train is on. They will die of you do nothing.  There is one person tied to track B.  You cannot reach the people to untie them in time, but you can flip the track switch to switch the train to track B.  Do you actively take action to kill one person?  It's murder to do so, even if it saves the lives of 10 other people.
So, do you murder one person to save 10?

Another common one, is, would you murder a Hitler as a baby, if you had a chance?

These are thought experiments, but real life examples have come up.  The point is, you can't universally say anything is morally right or wrong because everything is conditional.

In general, I would personally go with the least harm thing.  The best moral choices are those that cause the least harm.  Then we all get to sit around defining and weighing what constitutes harm. 

I would say that there is a core morality that is, if not universal, so common that it transcends culture. The problems are painful to work through, but only because the ideal option (no one getting hit by a train) is off the table. It's actually hard to train soldiers to kill the enemy without remorse, let alone civilians, so a lot of their training is to get them to a point where they fire at the enemy without much thought. Of course, once you get them there, it's possible they will take it even farther and commit what are considered atrocities, at least partly because we've unanchored them from their moral instincts and placed them in situations where they must kill to survive.

Some ways of living are objectively better than others, given human well being as a standard. We have 'moral instincts' but we also have 'immoral instincts'; or if you like, prosocial and antisocial instincts; that are in tension and can shift in prominence with situational changes. A previously perfectly nice guy may strangle you for your oxygen so he can live a little longer if you're both trapped underwater with a limited air supply; though I think that guy is the exception rather than the rule, a criminal might regard getting your money as a matter of survival, and people will do things to survive they would never do otherwise.

I know I'm rambling. My main point is that there can be very basic morality common to humans that is difficult to forumlate in general rules without going to extremes and specifying motivation (e.g., there are no circumstances where it's okay to use a live human baby as a hockey puck in an otherwise-regular hockey game for sport).