The real problem with the CNBC debate was more profound than mere ideological bias. The deeper problem was that the moderators were overwhelmingly biased toward "tough" questions when they would have been better off lobbing softballs. The truth is that easy questions are often harder to answer, while tough ones let con men skate by.

The CNBC debate resembled the three other debates televised thus far, and most high-profile interviews with politicians in general. There's a bias toward questions that turn the discussion into a combat sport between moderators and participants and mask politicians' real weaknesses.

Next time around, debate moderators ought to try something radical: think up a few topics that haven't been discussed much in the campaign and ask some softballs about them. See what the politicians say. And let them argue about each other's answers.

Politicians win when the moderator argues

We've all seen episodes of Law & Order in which at some crucial moment Jack McCoy delivers a thunderbolt of a question that smashes a witness's psychic defense mechanisms. They break down on the stand, either confessing to some deep secret or simply weeping in a stunned silence that speaks volumes.

We also all recognize that while this is fun television, it's not actually how trials work.

Yet many television personalities seem to think it is how live interviews with politicians work. Anderson Cooper kicked off the Democratic debate with this question:

Secretary Clinton, I want to start with you. Plenty of politicians evolve on issues, but even some Democrats believe you change your positions based on political expediency. You were against same-sex marriage. Now you're for it. You defended President Obama's immigration policies. Now you say they're too harsh. You supported his trade deal dozen of times. You even called it the "gold standard". Now, suddenly, last week, you're against it. Will you say anything to get elected?

It's as if CNN expected Hillary Clinton to melt in front of the audience and admit that she's a power-crazed flip-flopper who would stop at nothing to win the presidency. Of course, she didn't break down, and Democrats watching the debate were probably annoyed by Cooper as they instinctively rallied around Clinton.

When the moderator asks an argumentative question — as many moderators have at all the debates — all the audience ends up seeing is a politician arguing with a journalist, letting everyone fall back on their ideological and partisan preconceptions.

"Easy" questions are harder to answer

By contrast, there are real examples of journalists wrecking politicians with relatively easy questions.

Consider Sarah Palin's disastrous response to Katie Couric asking her to name the pros and cons of TARP.

The thing about Couric's question is it was actually a somewhat challenging question to answer. Most people are not that conversant in banking policy or macroeconomic stabilization, and don't have a particularly clear grasp of the best arguments on either side. But it's not a "tough" question at all. It's incredibly polite. It's friendly. And it's a clearly legitimate thing to ask — TARP was a major policy issue in the news. Palin's response is doubly damning. She clearly has no idea what she's talking about, and she equally clearly lacks the self-confidence and good sense to admit that she doesn't know.

But the only reason Couric was able to smoke her out is that the question was such a softball. A "tougher" formulation — a sharply worded, pointed question about how isn't it true she's not ready and not up for the job — would have simply invited a parry about the condescension of the liberal media. The dodge could have led to a badgering follow-up, of course, but then you'd just have a politician and a journalist bickering, leaving the audience to simply stick with their preconceptions. But Couric — wisely — tossed Palin softballs and let her amateurish responses speak for themselves.

Rick Perry's infamous "oops" moment came in response to a very bland John Harwood question asking whether Mitt Romney deserves credit for winning in a blue state. The polite, nonconfrontational framing of the question gave Perry plenty of space to ruminate, and he ended up humiliating himself.

Hard questions are easy, because we grade on a curve

Self-consciously "tough" questions with hostile framing end up setting a low bar for the politician answering the question. Consider an issue from the Democratic side: Bernie Sanders on socialism. Whenever this comes up, Sanders delivers one or another version of a so-so canned series of lines praising Nordic welfare states. How well that actually plays in practice ends up depending a lot on how "tough" the question was — with tougher, more hostile questions leading to more effective responses.

In the CNN Democratic debate, Anderson Cooper raised the issue in the context of a confrontational, condescending, and hostile question: "A Gallup poll says half the country would not put a socialist in the White House. You call yourself a democratic socialist. How can any kind of socialist win a general election in the United States?"

Contrast that with Ezra Klein, who simply tossed Sanders a straight pitch: "Tell me what it means to be a socialist."

Sanders said essentially the same thing in response to both questions, and it's a pretty good answer. But precisely because Cooper asked with the tone of a jerk looking to trip him up while Klein asked with the tone of a nice young man who's curious to hear the answer, Sanders winds up looking better in response to Cooper than to Klein.

"Well, we're gonna win, because first we're gonna explain what democratic socialism is," Sanders snaps at Cooper. It's an effective rejoinder because it makes Sanders seem courageous — how many other American politicians are willing to defend a form of socialism on national television? If you're a liberal, it's exactly the sort of moment that makes you like Sanders.

In the Vox interview, though, Sanders can't make the issue where he's willing to defend his socialism, so he actually has to explain it. And there, his canned answer ends up sounding canned and a little shallow.

Try asking some softballs

My fondest wish is that in future debates, we will get some softball questions. I follow US politics much more closely than the average person, but there are a lot of topics where I don't really know what many of the leading contenders think. Debates would be a good way to find out who thinks what about these issues, and who has even bothered to think about them.

Different people are interested in different things, but here are some questions I would ask if I got to moderate a debate:

Roughly how much should we cut domestic spending? (For a Democrat, you could ask how much they want to increase spending.)

What would be an appropriate amount of money to spend on the military?

How would you approach America's relationship with China?

What kinds of changes should we make to federal transportation policy?

Should the Federal Reserve raise interest rates at its December meeting or hold off a bit longer?

Roughly how many immigrants should be coming to the US legally?

Is the Export-Import Bank a good idea?

Do we do too much or too little to encourage homeownership in America?

The federal government runs a lot of programs. Are there any that you think are really good and deserve more money? (For a Democrat, you could ask about bad programs that should be eliminated.)

Why are so many more Americans leaving California than moving there?

Should we try harder to promote human rights and democracy in Saudi Arabia?

These aren't really "tough" questions. But they're hard to answer, because they ask about difficult topics on which reasonable people disagree. It would be interesting to see what the people who want to be president have to say about them.

Let the candidates be tough on one another

Softball questions are underrated in general. But the case for softballs is especially strong in the context of a debate for the simple reason that the various people onstage are engaged in a zero-sum conflict for political office. Let the candidates be "tough" on one another if anyone is going to be tough.

Doing that, of course, requires the network hosts to be willing to take a little bit of a chance and let the candidates — rather than the moderators — be the stars of the show. But at the end of the day, it's the presence of the presidential candidates that makes the debate worth watching. The most useful thing the moderators could do is raise some neglected topics and let the politicians argue about them — while staying out of the way.

It's not fashionable to say in media circles, but the fact of the matter is that journalists simply aren't fascinating or well-regarded enough to be the stars of the show. Toss some easy pitches and see if anyone can hit them out of the park.