Why should people care about the past or the future? That may sound like a perverse question, but it’s at the center of two recent stories — one involving the Islamic State’s destruction of antiquities at Palmyra in Syria, and the other a presidential warning about damage to the planet decades hence.

The unpleasant, amoral question usually doesn’t get asked: Why should people give a hoot about their ancestors or descendants? What constrains us from simply acting selfishly?

Certainly, we don’t have any formal obligation to preserve old relics, unless they’re protected by law. And in the march of progress, we frequently bulldoze old structures and barely notice. As for the environment, why shouldn’t people maximize their self-interest today, even if it harms the welfare of descendants most of us will never meet?

In the age of Donald Trump, the cult of self-interest occasionally seems like an article of the Bill of Rights. But it’s likely that we’re programmed, as a species and a republic, to be more generous. Parents care about their children (and vice versa) because it helps us survive. Let’s look at the recent examples that test the proposition.

On Aug. 25, Islamic State activists posted on social media photographs of what they claimed was the destruction of the “Temple of Baal Shamin” in the nearly 2,000-year-old Roman city of Palmyra, which the extremists had captured in May. The photos showed two fighters carrying a barrel of explosives into the temple, charges placed astride three ancient columns, and then a mushroom cloud of debris.

A ghastly satellite image was released Tuesday by a United Nations agency, confirming this assault on history. It showed rubble where the walls of the site’s main building once stood. Maamoun Abdulkarim, the head of Syria’s department of antiquities and museums, told BBC Radio that the action was a “catastrophe” and that he was “very sad and very pessimistic” for the future of the site.

The Islamic State militants didn’t explain their actions. But past statements have indicated that they view such ruins as creations of a polytheistic religion and culture they reject. This disregard for the heritage of “others” is sadly not a unique view: During the centuries of European exploration and colonization, many native shrines and artifacts around the globe were destroyed. The United Nations today designates World Heritage sites (such as Palmyra) in part to assert universal standards for preservation. U.N. member nations implicitly recognize the obligation of stewardship.

President Obama this week invoked our responsibility to be unselfish about the future. In a speech Monday in Alaska he painted what  The Associated Press called a “doomsday scenario” if climate-change trends aren’t reversed: “More drought; more floods; rising sea levels; greater migration; more refugees; more scarcity; more conflict. ... We will condemn our children to a planet beyond their capacity to repair.”

A confirmed advocate of self-interest might respond: Well, my children will just have to cope. Many adults, after all, spend down their savings to live well in the present, rather than pass along a larger legacy to their kids. This sensibility is implicit in arguments that the welfare of the living should take precedence over the state of the planet in an unknowable future. 

But do Americans really believe in this radical version of selfishness? There’s considerable scholarship arguing the opposite. As my colleague Steven Pearlstein, who now teaches economics at George Mason University, argues in a chapter titled “Is Greed Good?” in a forthcoming book, we’re programmed for intergenerational fairness and generosity. Indeed, our republic was founded as a commonwealth, to protect values that were taken to be “self-evident.” Every officeholder takes a vow to “preserve, protect and defend” the nation.

“The only pure individualists are hermits,” argues Joshua Greene in his recent book, “Moral Tribes.” He asks: “Why should any creature be social? Why not just go it alone? The reason is that individuals can sometimes accomplish things together that they can’t accomplish by themselves. This principle has guided the evolution of life on earth from the start.”

Part of why the United States has been so successful is that Americans are not just greedy. They cooperate. They build roads and airports and cyberspace that can be shared. They provide for the common defense. As Pearlstein observes, history teaches us that societies like ours, which temper raw greed with collective values, do better than those that don’t.

When we feel a revulsion at the destruction of the past or a threat to the future, what we are really affirming is human survival.

By David Ignatius

David Ignatius’ email address is davidignatius@washpost.com. — Ed.

(Washington Post Writers Group)