Singer believes that members of affluent societies should be giving far more of their time and money to effective charities than they currently do. This leads him to question what factors (especially psychological ones) limit the amount that people give.

Some limitations on giving result from assumptions about the way the world is and the way it should be. The naturalistic fallacy, a mistake in the reasoning process first articulated in the 18th century by Scottish Enlightenment philosopher David Hume, states that facts about the way the world is say nothing about the way the world should be. This fallacious reasoning assumes that nothing needs changed—that nature is the arbiter of right action. Singer, contending with those who implicitly accept this fallacy, writes:

The fact that we tend to favor our families, communities, and countries may explain our failure to save the lives of the poor beyond those boundaries, but it does not justify that failure from an ethical perspective, no matter how many generations of our ancestors have seen nothing wrong with it (41).

It is normal that giving is often limited to one’s family, community, church, or country, but this does not make it right.