It was a striking move for the oldest continuously published magazine in the United States and one its editor in chief, Laura Helmuth, said was both carefully considered and entirely necessary. (Helmuth previously worked as The Washington Post’s science editor.)

Four years ago, the magazine flagged Donald Trump’s disdain for science as “frightening” but did not go so far as to endorse his rival, Hillary Clinton. This year, its editors came to a different conclusion.

“A 175-year tradition is not something you break lightly,” Helmuth told The Post on Tuesday. “We’d love to stay out of politics, but this president has been so anti-science that we can’t ignore it.”

The endorsement is one of several occasions during the president’s tenure when the scientific community has denounced President Trump’s beliefs and policies. The 2017 March for Science rallied the community to defend its institutions from budget cuts and undermining by Trump and his appointees. A growing movement to get scientists to run for political office emerged ahead of the 2018 midterm elections. Most recently in May, the medical journal the Lancet blasted Trump in an editorial for his “inconsistent and incoherent” coronavirus response.

Scientific American’s 1,400-word editorial is as much an endorsement of Biden as it is a catalogue of Trump’s hostility to science throughout his term.

In a nod to Trump’s embrace of anti-science conspiracy theories, Scientific American editors compared the people each candidate turns to for expertise and insight. Biden’s panel of public health advisers include figures such as former U.S. Food and Drug Administration chief David Kessler and immunologist Rebecca Katz.

Ultimately, it was Trump’s response to the novel coronavirus that created a new sense of urgency for Scientific American’s editors, Helmuth said.

“We’ve seen the consequences of this so tragically with the coronavirus pandemic. It will be 200,000 people who have died from the virus, and a lot of that is on his hands,” Helmuth said of Trump.

In a statement, Trump campaign spokesman Tim Murtaugh defended the president’s handling of the pandemic, writing, “President Trump has listened to the medical experts every step of the way to fight the coronavirus, and the experts agree that the restriction on travel from China saved thousands of American lives."

Despite the excoriation of the president for his anti-science stance, Helmuth stressed that the editors wanted their endorsement to be fact-based and evidence-backed — not partisan.

“We never used the world ‘Republican’ or ‘Democrat’; it’s strictly about these two people,” Helmuth said.

In such a politically fractured environment, Helmuth acknowledged that editors were concerned how an endorsement might read, and if it would undermine the public’s faith in scientific institutions like theirs.

Scientific American’s track record of not endorsing candidates is what could ultimately give its endorsement more weight, according to Paul Beck, a political scientist and professor emeritus at Ohio State University.

“An endorsement from an organization like that — that has been in the past above politics — would carry considerable weight with their audience,” Beck told The Post, calling the Scientific American endorsement “powerful.”

For an organization that has avoided political endorsements for so long to join the fray is unusual, Beck said — though when it comes to the 2020 race, he said, nothing surprises him.

“You have a truly anti-science president,” Beck said, “and the scientific community by and large has been appalled at what has come out of the president’s mouth and come out of Washington.”

The fractured news environments and hyper-partisanship of American politics have diminished the power of political endorsements compared with election cycles past, Beck said. Endorsements could still have an effect on undecided voters, whom he estimated at a small percentage of the electorate, in the realm of 10 percent or less.

When it comes to potential Trump voters, an endorsement from a respected outlet like Scientific American won’t move the die-hard supporters, he said, but it might sway Republicans or independents who already have doubts.

“You can imagine if I’m a subscriber to Scientific American, and a Republican, I might say, ‘Well, see, maybe I shouldn’t vote Republican this time around,’ ” Beck said.

Helmuth said that after careful consideration of what an endorsement would mean, the decision by Scientific American’s editorial board was ultimately unanimous.

“We cover the intersection of scientific issues that have political relevance,” she said, “but this is the first time we’ve said, ‘If you care about science and you’re a voter, there’s an obvious choice.’ ”

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