how much of what we think our values are, is actually the result of not thinking things through, and not realizing the implications and symmetries that exist?

A very, very large portion.

When I was a child, I read a tract published by Inter-Varsity Press called "The salvation of Zachary Baumkletterer". It's a story about a Christian who tries to actually live according to Christian virtues. Eventually, he concludes that he can't; in a world in which so many people are starving and suffering, he can't justify spending even the bare minimum food and money on himself that would be necessary to keep him alive.

It troubled me for years, even after I gave up religion. It's stressful living in America when you realize that every time you get your hair cut, or go to a movie, or drink a Starbucks latte, you're killing someone. (It's even more stressful now that I can actually afford to do these things regularly.)

You can rationalize that allowing yourself little luxuries will enable you to do enough more good to make up for the lives you could have saved. (Unlikely; the best you can do is buy yourself "offsets"; but you'd usually save more lives with more self-denial.) You can rationalize that saving lives today inevitably leads to losing more lives in the future. (This carried me for a long time.) But ultimately, the only way I find to cope is not caring.

Recently, Michael Vassar told me I was one of the nicest people he knows. And yet I know that every day, I make decisions that would horrify almost everyone in America with their callousness. Other people act the same way; they just avoid making the decisions, by not thinking about the consequences of their actions.

I'm not a nice person inside, by any stretch of the imagination. I just have less of a gap between how nice my morals tell me to be, and how nice I act. This gap, in most people, is so large, that although I have morals that are "worse" than everyone around me, I act "nicer" than most of them by trying to follow them.