Sen. John McCain (R-Ariz.) arrives at the Capitol last month. (AP Photo/J. Scott Applewhite, File)

As Sen. John McCain R-Ariz.) battles brain cancer, Americans are rallying to his side and reflecting on his political legacy. Republicans and Democrats alike are calling McCain — perhaps the country’s best-known former prisoner of war — a hero.

McCain is a decorated naval veteran who was held in captivity for five-and-a-half years during the Vietnam War. In 2015, when candidate Donald Trump said McCain wasn’t a war hero because “I like people who weren’t captured,” politicians from Hillary Clinton to Ted Cruz defended the Arizona senator.

Implicit in the praise for McCain is this idea: Whatever else divides us, heroism unifies. As with obscenity and good taste, we know heroism when we see it. A universally shared definition of heroism supposedly provides a common reference point for the public, politicians and the media. The media, our leaders and the public as a whole have similar lists of icons they revere, and value the same kinds of extraordinary attributes that make a person heroic.

But not so fast. Our research shows that, yes, many of today’s leaders and journalists assume that we all agree on who’s a hero — but that the public is more skeptical about heroism. Public agreement over McCain’s identity as a hero appears to be the exception, rather than the rule.

Here’s how we did our research

We used mixed methods to come to our conclusions. We drew on existing and original polling from the 1930s to today, on presidents’ and congressional members’ remarks going back to the 1900s, and insights from focus groups that created in-depth conversations with four post-World War II generational groups.

From these sources, we found that the gap between the views of politicians and journalists on the one hand and ordinary citizens on the other has gone through a gradual but measurable historical shift. And it’s a shift with important implications for 21st-century politics.

Once upon a time, heroes were few

It used to be that the press and politicians didn’t talk much about heroes. When they did, it was about figures who shared some basic traits: heroes took on risk to help others, often in the name of some cause bigger than any one person.

For example, a news story from 1905 described a “modest hero” who jumped into a hole in the ice in a New York City park to save a drowning child. President Warren G. Harding’s 1922 State of the Union address lauded the heroism of U.S. men and women during World War I who helped to restore a “tranquil order” of peace, but individual heroes did not appear frequently in major presidential remarks through the first seven decades of the 20th century.

Our work finds a similar set of attitudes in the public — a viewpoint that endures through today. When pollsters in 1938 asked Americans about President Franklin D. Roosevelt’s heroism they were cautious: 22 percent said they hoped Roosevelt would not be regarded as a hero in a decade’s time, while 29 percent further indicated they just didn’t care about the president’s status as a hero.

Politicians and journalists talk increasingly about heroes

Over time, we find the public has stuck with this reluctance to recognize and celebrate heroes. Meanwhile, major media outlets and political addresses have increasingly invoked heroism to tell stories, foster public relations and entertain.

For today’s elected officials, celebrating the heroism of a fallen cop, a decorated soldier or even an ordinary constituent is non-threatening, broadly appealing and even non-partisan. In June alone, House and Senate members made dozens of references to “heroes” in remarks published in the Congressional Record.

For instance, they praised as heroes African American “revolutionary war patriots” from Kentucky; 21st-century soldiers suffering from “post-traumatic stress”; democracy activists in Hong Kong; and even Paul Bunyan, as a “larger-than-life folk hero who embodies … the willingness to work hard.”

For the media, the surge in hero reporting over the past five decades is not about getting votes or steering policy. Instead, stories about heroes are part of an almost desperate strategy to boost readership and viewership.

News outlets and other content providers use hero narratives as a familiar and dramatic way to package content. Thus, CNN reported on a retired Army captain as a hero for training service dogs to help disabled military veterans – veterans whom she in turn described as “my heroes.”

A recent story about the Lebowski Fest — an annual festival in Louisville, devoted to the 1998 film “The Big Lebowski” and its offbeat characters — called The Dude a fitting if flawed hero for our “crazy times.”

And media outlets such as Huffington Post and the New York Daily News encourage readers to nominate heroes for praise and future coverage. These flashy stories, which encourage the audience to participate, are ways to keep readers’ attention at a time when competition for their time is fierce.

Most Americans aren’t as quick to name heroes as their leaders are

But the hero touchstone has not been eagerly seized by today’s public. Surveys consistently reveal Americans’ reluctance to anoint heroes. Despite the frequent presentation of heroes by the media and our elected officials, typically a majority of those polled are unable or unwilling to name a hero in public life. Furthermore, a 1997 poll found that 91 percent of those polled thought that someone had to actually “save lives” to be considered a hero — as opposed to simply going to “great lengths” for others.

Similarly, in our focus groups, we found a wide span of ordinary people — from members of the Silent Generation (born between 1928 and 1945) to today’s millennials (those born between 1981 and 1997) — expressing skepticism about the “prepackaged” heroes handed to them by elites. As one focus group member argued, “The press builds up heroes very quickly and shoots them down very quickly.” A baby boomer told us that “we can’t depend on government to do what it’s paid to do now, let alone to create an awareness of good people in the world and their heroic efforts.”

On the whole, we find the abundant heroism celebrated by the media and political figures resisted by We the People. Most of the public thinks that heroism requires something exceptional and rare: high standards of valor, the assumption of great personal risk and promoting a cause larger than oneself. In a 2014 poll, 92 percent of our respondents agreed that someone could become a hero by risking “personal safety while helping someone in danger” while only 28 percent said that rising “to the top of one’s profession” was sufficient.

Here’s why this matters

This split between the public and elites is apparent in headlines, speeches, polling results and our focus groups. As one of our group participants argued, it used to be that if “you saved someone, you got a small print on page two of the newspaper” but today our leaders and “the press gets carried away and then starts assigning the word hero rather easily.”

This perceived hero gap is significant for three reasons.

1. A decline in trust. It is a general marker of Americans’ uncertainty about their institutions and leaders. Today’s doubts about how the media and government speak about heroes reflect deep misgivings about the legitimacy and veracity of these entities. Indeed, heroism seems to be caught up in a general wave of skepticism about major American institutions such as marriage, religion and government, a measurable decline in trust that has been unfolding since the 1960s.

2. A reluctance to get involved. Researchers note that while many Americans are politically ignorant and uninterested, they use shortcuts or cues (such as party labels) to help them make political decisions. Scholars have argued that heroes can get Americans to pay attention or even contribute to social movements or national defense. But when people doubt politicians’ and media messages about heroism, this tool may be unavailable.

3. Heroes can unify. Finally, heroes can be a way to bring together a divided nation. This possibility is limited when we are dubious about the organizations that talk to us about these figures. As noted, two-thirds of Americans identify McCain as a “war hero,” a result that includes majorities of Republicans, Democrats and independents.

But McCain may well be the rare — if not unique — bipartisan hero, at least among those still living. When the Gallup polling organization found that Presidents Obama and Trump were among the most “admired” men in the world, results were strongly skewed by partisan attitudes. We are deeply suspicious of our political opponents, a reality that makes governing difficult and produces a hostile environment for national heroes.

Bruce Peabody and Krista Jenkins are professors of political science at Fairleigh Dickinson University and the authors of “Where Have All The Heroes Gone? The Changing Nature of American Valor.”