Reporters and members of the media ask questions at a press briefing at the White House. (Jabin Botsford/The Washington Post)

American journalism has suffered from many ailments at many different times, but every opinion on what ails it past, present and future is just an opinion, not science: just a proposition that cannot be proved, only found by any reader to be more or less persuasive.

The late Post columnist Michael Kelly often reminded my radio audience that journalism was a craft, not a profession. No licensing agency acted to credential “journalists.” You take up the craft, practice it, got better at it (or not), flourish (or not). There aren’t any rules that bind, nor oaths or codes to take or break: just a craftsman’s pride in doing good work, occasionally recognized in ways that mattered by fellow craftspeople.

I have been part of this guild since 1989, in print, over the radio for Salem Media and on television, both for PBS and now for NBC. I’ve conducted more than 10,000 interviews and moderated hundreds of non-broadcast conversations.

My most recent interview of some note and much fun was with Henry Winkler, loved by those 50 and older for his “Happy Days” role as “The Fonz,” by millennials for “Arrested Development’s” Barry Zuckerkorn and now the co-author along with Lin Oliver of the Hank Zipzer series of young adult and children’s novels about a dyslexic Manhattan boy, based on Winkler’s own life.

The reaction online to my interview with Winkler followed the now-standard bifurcation of American political discourse of 2017 into up or down, right or wrong. If you are a “core supporter” of President Trump, you hated the interview (and by extension Winkler). If you loathe Trump, your opinion of Winkler soared. The “Trump Effect” is to take any topic touching on the president, filter it through your Trump bias and conform it to a preexisting disposition.

I asked Winkler to talk politics as a test case for this proposition. He had weighed in for President Barack Obama in 2008, so I expected and received a negative take on Trump. What I wanted to see was whether his political views — athough I disagreed with them, they were presented with logic, reason and skill — would negatively or positively affect viewers’ impressions of Winkler the man. Judging from the anecdotal evidence, the answer is a resounding “Yes!” Increasingly, people are basing their views on everything — including other people — upon those things’ relationship to Trump and those people’s views of him.

The media is not apart from this phenomenon. In fact, it may be the driver of it. And that represents a profound illness for the craft.

The medical condition most akin to what is happening to journalism generally and to Manhattan-Beltway-elite journalism in particular is glaucoma, a disease that takes vision gradually, with no early warning signs or painful symptoms. Journalists are losing the full scope of our collective vision, coming to see every story through the lens of Trump, often through a lens colored by hostility toward him. Detachment about the president and his actions — genuine objectivity — is rare and getting rarer. Tell me the “Trump subject” and the pundit or reporter speaking to it — and there is an increasingly small difference between those roles — and I am pretty good at predicting not just the response but also the decibel level and the precise adjectives.

This is new for the media. That Manhattan-Beltway media elites skew left on the American political spectrum is not a bulletin. What is new is the transparency of that bias and, with regard to the president, a celebration of “resistance” to him — indeed, contempt for him. “Journalists” want very much for their audiences to know where they stand on the president and all the president’s men (and women).

This is “virtue signaling,” an exercise in thinking oneself on the “right side of history” and within what C.S. Lewis called the “The Inner Ring.” The problem with this obsession of positioning vis-a-vis Trump is that it is blinding a large and talented segment of the guild to the real stories: North Korea is a run by a gangster whose only product worth buying will soon be nuclear weapons. Iran fleeced the Obama administration and combines the nascent production capability of North Korea with an “end times” philosophy of apocalyptic fervor. The Budget Control Act is crippling the military in perilous times when it needs not budget gimmickry but serious resupply over a decade. The immigration reform the country needs is obvious and within reach but cannot be described because it might credit the president’s demand for a border barrier. The “blue slip” is wreaking havoc on the judicial confirmation process.

Many in the craft are fond of saying something like “the presidency is broken,” “the president’s conduct is unprecedented” or that we face a “constitutional crisis.” Journalist, heal thyself. At a moment of peril on many fronts, the craft is collapsing into rote condemnation of a president who won a large majority of electoral college votes. Probably because of the deep and wide contempt for the media elites who have appointed themselves the guardians of a tradition they know little of and respect less: liberty.