But I wanted to mention something I learned recently that has helped me a great deal in understanding the discussion about the topic, an insight from Social Psychologist Jonathan Haidt that he presents in his book The Righteous Mind. Here's what he discovered: intuitions come first, strategic reasoning second.
Here's how that plays out:
Moral intuitions arise automatically and almost instantaneously, long before moral reasoning has a chance to get started, and those first intuitions tend to drive our later reasoning. If you think that moral reasoning is something we do to figure out the truth, you’ll be constantly frustrated by how foolish, biased, and illogical people become when they disagree with you. But if you think about moral reasoning as a skill we humans evolved to further our social agendas—to justify our own actions and to defend the teams we belong to—then things will make a lot more sense. Keep your eye on the intuitions, and don’t take people’s moral arguments at face value. They’re mostly post-hoc constructions made up on the fly, crafted to advance one or more strategic objectives.In essence, as I understand it, our first intuitive response is whether something feels morally right or wrong. And based on that feeling, we marshal our arguments to justify our emotional and intuitive response.
This is true on all sides of the argument, of course. I'm not saying one group is being rational and the other is flying off the handle. I guess I'm simply saying be aware of how you feel about the topic, and let's not fool ourselves that we are being systematic and rational on this issue.
Introductory chapter of Haidt's book is here.