Excerpt from The Kindness of Strangers by Michael E. McCullough, plus links to reviews, author biography & more

Many evolutionary perspectives on generosity toward strangers also fail to take recent human history seriously enough, no doubt because evolutionists are primarily interested in natural selection, which needs eons to create complex functional design. As a result, they don't spend enough time considering the causal pathways by which our generosity toward strangers has effloresced over the past ten thousand years.

Finally, evolutionists also tend to overlook two important mental faculties. The first is our ability to follow our incentives. Like other animals, we can track the paths of action that will lead us to the things we care about—food, shelter, clothing, fame, a city free of disease and crime, a prosperous national economy, fidelity to our ethical convictions, a meaningful life. We can then construct courses of action that will lead us closer to those things we desire. Second, and relatedly, modern evolutionists often overlook our capacity for reason. Humans evolved both to produce reasons—that is, to offer justifications for their beliefs and convictions— and to process reasons—that is, to evaluate the justifications that others offer for their beliefs and convictions. For too long, evolutionists have been allergic to psychological explanations for behavior that rely on seemingly general-purpose cognitive abilities such as "tracking incentives" and "reasoning." However, as we will see, these faculties are indispensable for a complete account of our concern for strangers today.14 You just can't explain it without them.

Fittingly enough, it was Darwin himself who fashioned our social instincts and our intellective powers into a scientific explanation for the vast expansion of human concern over the past ten millennia. "Any animal whatsoever, endowed with well-marked social instincts, the parental and filial affections being here included," Darwin wrote,

would inevitably acquire a moral sense or conscience, as soon as its intellectual powers had become as well, or nearly as well developed, as in man. For, firstly, the social instincts lead an animal to take pleasure in the society of its fellows, to feel a certain amount of sympathy for them, and to perform various services for them... . But these feelings are by no means extended to all the individuals of the same species, only to those of the same association.

Darwin surmised that the "well-marked social instincts" that motivate our concern for kith, kin, and compatriots, in spite of their parochiality, were recruited into service only very recently in human history to promote our regard for the welfare of all of humanity. And it was our capacity for reasoning, he averred, that did the recruiting:

As man advances in civilization, and small tribes are united into larger communities, the simplest reason would tell each individual that he ought to extend his social instincts and sympathies to all the members of the same nation, though personally unknown to him. This point being once reached, there is only an artificial barrier to prevent his sympathies extending to men of all nations and races.

Later in the same chapter from his 1871 book The Descent of Man, Darwin drove his argument home again, almost apologetically, as if he were worried that he had begun to beat a dead horse:

The moral sense perhaps affords the best and highest distinction between man and the lower animals; but I need say nothing on this head, as I have so lately endeavoured to shew that the social instincts—the prime example of man's moral constitution—with the aid of active intellectual powers and the effects of habit, naturally lead to the golden rule, "As ye would that men should do to you, do ye to them likewise"; and this lies at the foundation of morality.

The argument I tender in this book is similar to Darwin's own, and it is a straightforward one. I argue that the kindness of strangers is built upon a surprisingly small number—four, in fact—of our evolved human instincts. These include two of the instincts that Darwin called our "social instincts"—our instinct for helping others in hopes of receiving help in return, and our instinct for helping others in pursuit of glory—as well as the instincts Darwin called our "active intellectual powers," especially our ability to track incentives and our capacity for reason.

Excerpted from The Kindness of Strangers by Michael E McCullough. Copyright © 2020 by Michael E McCullough. Excerpted by permission of Basic Books. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.