When I applied to medical school, an experienced doctor offered me some advice: ‘Don’t give them reason to think you’re a “wounded healer”. They’re suspicious of that.’ The term is Carl Jung’s, by which he meant that personal difficulty is a powerful spur for joining a caring profession, but the results of such motivations are not always constructive. If you appear too altruistic, questions may surface about whether you might, in some way, be damaged.

So what about those people who don’t just do their job, but dedicate their lives to helping others? The New Yorker staff writer Larissa MacFarquhar examines our ambivalence about goodness in her brilliantly thoughtful new book. Heroes, Pollyannas, saints, sentimentalists, killjoys, people-pleasers, martyrs, call them what you will, Strangers Drowning interweaves the history and philosophy of altruism with real-life stories of ‘do-gooders’ whose urge to serve goes beyond the call of duty. Many of MacFarquhar’s characters planned to become doctors or nurses, but then chose to do something greater. We follow a vegan on a mission to rescue chickens, a couple who end up adopting 20 children, the founder of a leper colony and a man who gives his kidney to a patient he has never met. After narrowly avoiding rape in her own home, one do-gooder runs after the intruders as they leave, asking, ‘Would you like a cup of coffee?’

A point of similarity between these eccentric figures is that they are undeterred by scale and distance. When considering human nature, Adam Smith had a dim view of the normal proportions of empathy. In The Theory of Moral Sentiments (which is not quoted by MacFarquhar but is everywhere present) he explains, half jokingly, that suffering which occurs close by, both logistically and emotionally, consumes us. If a man were due

to lose his little finger tomorrow, he would not sleep tonight; but provided he never saw them, he will snore with the most profound security over the ruin of a hundred million of his brethren, and the destruction of that immense multitude seems plainly an object less interesting to him than this paltry misfortune of his own.

Yet for the do-gooders in Strangers Drowning, victims out of sight are certainly not out of mind. Unknown foreigners are for them no less worthy of attention than their own families. Some are overwhelmed when they contemplate the plight of individuals, helping as best they can but haunted by inadequacy. Others feel at a remove from their fellow men, driven to humanitarian projects not out of empathy so much as a colder rationality that knows ‘a million pounds could save about a hundred thousand years of healthy life’. At an extreme, this utilitarian mindset can turn on the human body as a mere cabinet of organs, ready for transplantation to alleviate illness. An unsettling side to altruism emerges here: making sacrifices for others, driven by a kind of ethical perfectionism, can be self-destructive. ‘Good enough’ is just an arbitrary point at which you end up letting yourself off the hook.

Tracing the motivations of her subjects, MacFarquhar resists clumsily joining the dots from childhood trauma, sexual abuse, fervent religious belief and mental illness to explain the moral hunger of these adults. But she does not deny that elements of their biographies might be relevant. Their stories are narrated with such even-handed curiosity, such compassion for human endeavour and forgiveness of fallibility, that you cannot help but share MacFarquhar’s admiration and see that these predicaments matter. Where I cannot agree is in the book’s claim that a do-gooder is distinctly different from the vast majority of us, content as we are with occasional acts of kindness and ‘virtue signalling’ on Facebook. There is surely a spectrum of selflessness along which we each find our place.

In the end, the book seems to ask us to relax our concern about the origins of goodness. Caring is more often prompted by feeling rather than theory, whether from personal experience or a visceral response to witnessed events. In a world where there are too many strangers drowning, from a boy washed up in an exceptional photograph to countless others who remain anonymous, it is more important to stir our better intuitions than to question where they come from. That there are do-gooders whose sense of duty is already stirred, we should be grateful.