Some do it to get into heaven, and some do it to get into medical school. Some do it because everyone else is doing it. Whatever the motivation, the number of health care volunteers heading from developed to developing countries has soared in recent years, with commentators straggling behind debating the merits of the stampede.

The reasons to applaud are self-evident: All the old epidemics are compounded by all the new ones, and the health-related fallout of wars and natural disasters never ends. If both skilled and unskilled labor can help, then surely those who provide such labor should do good, feel good and learn much.

Not necessarily, critics say. Some would concur instead with an opinion published by a Somali blogger in The Guardian in 2013 and quoted by the sociologist Judith Lasker in “Hoping to Help: The Promises and Pitfalls of Global Health Volunteering” — “The developing world has become a playground for the redemption of privileged souls looking to atone for global injustices by escaping the vacuity of modernity and globalization.” (Read an excerpt.)

And indeed, as Dr. Lasker watched groups of American and Canadian volunteers in matching T-shirts surging through the Port-au-Prince airport two years after Haiti’s disastrous 2010 earthquake, she was reminded of nothing so much as “the weekly Saturday turnover at American time-share vacation resorts.”