Why Do We Disagree about our Obligations to the Poor?

People disagree about whether individuals in rich countries like the United States have an obligation to aid the world's poorest people. A tempting thought is that this disagreement comes down to a non-moral matter. I argue that we should be suspicious of this view. Drawing on psychological evidence, I show that we should be more pessimistic about our ability to attribute the disagreement to a difference in factual beliefs.