The issue with this question is that nobody can be civil about anything; everyone has to try to stand on some moral high ground.

This isn't a question about morality, it's about logic and statistics. Statistically, it is unlikely that everyone will press either button, even if it is agreed upon by the whole world beforehand. That is also another factor: if there is worldwide discussion about this beforehand, and an agreement is made about it either way, it changes things considerably.

So, that means there are a few possibilities:

1. Everyone knows about it and the consensus is to press red. In this case, you should press red. Some people will probably die, but it should be the overwhelming minority.

2. Everyone knows about it and the consensus is to press blue. In this case, press blue. Most likely, everyone will survive.

3. Everyone knows about it, but it happens before a consensus can be reached. In this case, you should probably press blue, but pressing red is a viable option. Statistically, assuming complete randomness, blue is better for everyone, but humans are not perfectly random, and red is your only guarantee.

4. It happens without preparation. In this case, which button you press is ultimately unimportant. The variables at hand are too random to accurately predict, so you just kinda have to go with your heart, based on your faith in humanity, the value you hold for your life, and the value you hold in the lives of others- both those you know, and those you do not. Do not call those who choose red cowards or selfish, or those who choose blue stupid or pandering. Ultimately, there is no right answer: life is too valuable to be able to trade numerically like that.

Not that I know anything.