Investing often creates moral dilemmas over goals: Should we aim to do well or to do good? Is it appropriate to invest in tobacco companies? Or in companies that sell guns to drug gangs?

The recent popularity of so-called impact investment funds, which promise to deliver decent returns while advancing social or environmental goals, is based on this unease. Foundations often find that these investment vehicles help them to do good both with the money that they spend on philanthropy and with the endowment assets that yield the returns on which their philanthropy depends.