The best explanation why people agree is that they have converged on true answers.
Are there any good arguments in defence of moral nihilism? I think not.
To kill or not to kill, that was the question that haunted me.
According to deontology it is wrong to kill an innocent human being, period.
There are some particular moral truths that I believe we have access to (such as the one not to inflict pain on a sentient being for no reason).
Global governance need not take a democratic form.