By Brett Stephens, Apr 28, 2017
When someone is honestly 55 percent right, that’s very good and there’s no use wrangling. And if someone is 60 percent right, it’s wonderful, it’s great luck, and let him thank God.

But what’s to be said about 75 percent right? Wise people say this is suspicious. Well, and what about 100 percent right? Whoever says he’s 100 percent right is a fanatic, a thug, and the worst kind of rascal.

— An old Jew of Galicia

In the final stretch of last year’s presidential race, Hillary Clinton and her team thought they were, if not 100 percent right, then very close.

Right on the merits. Confident in their methods. Sure of their chances. When Bill Clinton suggested to his wife’s advisers that, considering Brexit, they might be underestimating the strength of the populist tide, the campaign manager, Robby Mook, had a bulletproof answer: The data run counter to your anecdotes.

That detail comes from “Shattered,” Jonathan Allen and Amie Parnes’s compulsively readable account of Clinton’s 2016 train wreck. Mook belonged to a new breed of political technologists with little time for retail campaigning and limitless faith in the power of models and algorithms to minimize uncertainty and all but predict the future.

“Mook and his ‘Moneyball’ approach to politics rankled the old order of political operatives and consultants because it made some of their work obsolete,” Allen and Parnes write about the campaign’s final days. “The memo that one Hillary adviser had sent months earlier warning that they should add three or four points to Trump’s poll position was a distant memory.”

There’s a lesson here. We live in a world in which data convey authority. But authority has a way of descending to certitude, and certitude begets hubris. From Robert McNamara to Lehman Brothers to Stronger Together, cautionary tales abound.

We ought to know this by now, but we don’t. Instead, we respond to the inherent uncertainties of data by adding more data without revisiting our assumptions, creating an impression of certainty that can be lulling, misleading and often dangerous. Ask Clinton.

With me so far? Good. Let’s turn to climate change.

Last October, the Pew Research Center published a survey on the politics of climate change. Among its findings: Just 36 percent of Americans care “a great deal” about the subject. Despite 30 years of efforts by scientists, politicians and activists to raise the alarm, nearly two-thirds of Americans are either indifferent to or only somewhat bothered by the prospect of planetary calamity.

Why? The science is settled. The threat is clear. Isn’t this one instance, at least, where 100 percent of the truth resides on one side of the argument?

Well, not entirely. As Andrew Revkin wrote last year about his storied career as an environmental reporter at The Times, “I saw a widening gap between what scientists had been learning about global warming and what advocates were claiming as they pushed ever harder to pass climate legislation.” The science was generally scrupulous. The boosters who claimed its authority weren’t.

Anyone who has read the 2014 report of the Intergovernmental Panel on Climate Change knows that, while the modest (0.85 degrees Celsius, or about 1.5 degrees Fahrenheit) warming of the earth since 1880 is indisputable, as is the human influence on that warming, much else that passes as accepted fact is really a matter of probabilities. That’s especially true of the sophisticated but fallible models and simulations by which scientists attempt to peer into the climate future. To say this isn’t to deny science. It’s to acknowledge it honestly.

By now I can almost hear the heads exploding. They shouldn’t, because there’s another lesson here — this one for anyone who wants to advance the cause of good climate policy. As Revkin wisely noted, hyperbole about climate “not only didn’t fit the science at the time but could even be counterproductive if the hope was to engage a distracted public.”

Let me put it another way. Claiming total certainty about the science traduces the spirit of science and creates openings for doubt whenever a climate claim proves wrong. Demanding abrupt and expensive changes in public policy raises fair questions about ideological intentions. Censoriously asserting one’s moral superiority and treating skeptics as imbeciles and deplorables wins few converts.

None of this is to deny climate change or the possible severity of its consequences. But ordinary citizens also have a right to be skeptical of an overweening scientism. They know — as all environmentalists should — that history is littered with the human wreckage of scientific errors married to political power.

I’ve taken the epigraph for this column from the Polish poet Czeslaw Milosz, who knew something about the evils of certitude. Perhaps if there had been less certitude and more second-guessing in Clinton’s campaign, she’d be president. Perhaps if there were less certitude about our climate future, more Americans would be interested in having a reasoned conversation about it.

https://www.nytimes.com/2017/04/28/opini...ainty.html?_r=0