Trump talks up his background as a business executive, but the background that really matters is his years as a reality TV star. All politicians need to be actors. But by nature or by experience, Trump is just far better at it than anyone else in the field. The magic is that every one of these roles and tones seems “authentic” to him. That is a large part of why he’s gotten this far, and why the Democrats have to take him seriously. Ronald Reagan, as an actor-presidential candidate, had nothing in the dramatic-skills range over Trump.

2) He may be the most ignorant person, about public policy, who has ever gotten this far in a presidential race. Note “ignorant,” or “uninformed,” rather than “unintelligent.” I’m sure that Trump would outdo Sarah Palin or Rick Perry on most tests of aptitude or general knowledge. But on knowledge of what a government does, or the issues a president really deals with, I think Perry and even Palin would come out well ahead.

In last night’s debate, Trump revealed that he still has no idea what Common Core is or how it works. At no point through the campaign has he evinced even the most basic knowledge of how the U.S. military is organized, what it does, how it stacks up against adversaries, or what its real problems are. (This started in an early debate with his obvious unfamiliarity with the term “nuclear triad.” That’s something most voters wouldn’t know but that anyone in government is supposed to. It’s the three-part delivery system for U.S. nuclear weapons: bombers, land-based missiles, and missile-equipped nuclear submarines.) He continues to complain about the Chinese government lowering the value of its currency, when in fact they’re trying hard to push the value up.

Here was his answer last night on long-term funding plans for Social Security. This is a contender for the least-informed comment any national-level candidate has ever made on the topic:

I will do everything within my power not to touch Social Security, to leave it the way it is; to make this country rich again; to bring back our jobs; to get rid of deficits; to get rid of waste, fraud and abuse, which is rampant in this country, rampant, totally rampant…. We've lost our jobs. We've lost everything. We're losing everything. Our jobs are gone, our businesses are being taken out of the country. I want to make America great again and I want to leave Social Security as is. We're going to get rid of waste, fraud, abuse and bring back business.

Social Security may have problems, but to list “waste, fraud, and abuse” among them is to show you have no idea what the real problems are. This was the exchange when CNN’s Dana Bash pushed him for details of how exactly he would change President Obama’s understanding with Cuba:

BASH: Just to be clear, Mr. Trump, are you saying that if you were president, you would continue the diplomatic relations or would you reverse them? TRUMP: I would want to make a good deal, I would want to make a strong, solid, good deal because right now, everything is in Cuba's favor. Right now, everything, every single aspect of this deal is in Cuba's favor. It the same way as the Iran deal. We never walked -- we never -- all we do is keep giving. We give and give and give.

To their credit, audience members in Miami, sophisticated on this topic, began hooting at the vacuity of Trump’s insistence on a “good deal” with no backup on what that meant. And then Marco Rubio dived in with an informed riff on the exact things he’d change in the Cuba arrangement.