Singer suggests that people who take an ethical approach to life often avoid the trap of meaninglessness, finding a deeper satisfaction in what they are doing than those people whose goals are narrower and more self-centered. He spells out what he means by an ethical approach to life and shows that it can bring about significant and far-reaching changes to one's life.

How Are We to Live? explores the way in which standard contemporary assumptions about human nature and self-interest have led to a world that is fraught with social and environmental problems. Singer asks whether selfishness is in our genes and concludes that we do not have to accept the bleak view of human nature sometimes believed to be inevitable, given our evolutionary origins.