The candidate: Donald Trump

The gaffe: Trump retweeted the following after a poll showed him slipping to second in the first caucus state: “@mygreenhippo #BenCarson is now leading in the #polls in #Iowa. Too much#Monsanto in the #corn creates issues in the brain? #Trump #GOP.”

The defense: Trump claims an intern was responsible:

The young intern who accidentally did a Retweet apologizes.

— Donald J. Trump (@realDonaldTrump) October 22, 2015

Maybe. But perhaps the intern’s name is Donald J. Trump. Trump has said he sometimes dictates tweets and sometimes does it himself—something reporters have witnessed—and this isn’t far off from other stuff he’s tweeted.

Why it matters (or doesn’t): It’s not a good idea to insult Iowa voters if you wish to win their vote. It’s also not a great idea to insult a company whose stock you own.

The moral: Never tweet.

The candidate: Jeb Bush

The gaffe: At a forum in Las Vegas (hosted by the Koch brothers-affiliated Libre Initiative, no less), he was asked who his favorite superhero was. (The question stipulated Marvel.) After mentioning Batman, he added: “I saw that Supergirl is on TV. I saw it when I was working out this morning. There’s an ad promoting Supergirl. She looked kind of—she looked pretty hot.”

The defense: Some people agree that Supergirl is, in fact, pretty hot.

Why it matters: For one, awkwaaaaard. For another, the question asked for Marvel characters, and Bush named two DC Comics characters—Batman and Supergirl. (And Bush says DC isn’t in his D.N.A.!) It’s neither easy nor wise to alienate female and nerd voters in one fell swoop.

The moral: There are much better ways to debunk the “war on women.”

The candidate: Hillary Clinton.

The gaffe: Asked to name the enemy she was most proud of late in Tuesday’s Democratic debate, Clinton answered: “Well, in addition to the NRA, the health insurance companies, the drug companies, the Iranians—[pausing for laughter]—probably the Republicans.” As Charles Cooke explains, declaring the entire opposition party your enemy makes it tough to run as a uniter.

The defense: Hey, who are we kidding? The line was played for laughs, but she’s probably being honest. She and many Republicans do probably consider each other enemies.

Why it matters (or doesn’t): It’s probably not bad politics in the Democratic primary. All night, Clinton tried to turn the conversation away from disagreements within the party and toward the broader difference with the GOP. But it could be used against her in a general election.

The moral: Don’t be your own worst enemy.

The candidate: John Kasich

The gaffe: At a town hall at the University of Richmond, Kasich responded to a student waving her hand to ask a question—about border security, it turned out—by cracking, “I’m sorry, I don’t have any Taylor Swift concert tickets.” It turns out she works for the campus paper, The Collegian, where she wrote a scathing column: “I didn’t go to a town hall forum for Taylor Swift tickets, Gov. Kasich. I went because it's my civic duty to be an informed voter. Please start treating me like one.” Weirdly, he also told another female student, “I’m sure you get invited to all of the parties.”

The defense: John Kasich loves Linkin Park and hates the Roots, so maybe no one should take his comments about music too seriously.

Why it matters (or doesn’t): Kasich has positioned himself as a bold truthteller, willing to tell the Republican base what it doesn’t want to hear. But that’s a risky strategy, and gratuitously alienating other important voter demos—young people, Taylor Swift fans—makes it riskier.

The moral: Dear John, I see it all now that you’re gone. Don’t you think I was too young to be messed with?

The candidate: Ben Carson. Third time today, doctor!

The gaffe: Here’s the candidate, speaking about the Umpqua Community College massacre on Fox News on Tuesday: “I would not just stand there and let him shoot me. I would say: ‘Hey, guys, everybody attack him! He may shoot me, but he can’t get us all.’”

The defense: Who even knows? At least one person at the college did try to stop the shooter. Carson’s answer on Wednesday was to double down on his argument: “I said what I would do. ... I would ask everyone to attack the gunman …. [I] “never saw a body with bullet holes that was more devastating than taking the right to arm ourselves away.” On Thursday, he started talking about Nazis.

Why it matters (or doesn’t): There’s a large bloc of voters who think the answer to the UCC massacre is more gun control. There’s a large bloc that thinks the answer is more armed “good guys.” But who believes that the answer is to blame the victims? One survivor told CNN: “I’m fairly upset he said that. Nobody could truly understand what actions they would take like that in a situation unless they lived it.”

The moral: When you shoot from the hip, sometimes you hit yourself in the foot.

The candidate: Ben Carson. Welcome back, doctor!

The gaffe: On CNN Thursday, Carson was asked about a passage in his book A More Perfect Union suggesting that gun regulation during 1930s Germany meant Jews couldn’t resist the Nazis. The Republican candidate didn’t flinch: “I think the likelihood of Hitler being able to accomplish his goals would have been greatly diminished if the people had been armed. There’s a reason these dictatorial people take the guns first.”

The defense: What Carson is saying here may be new to many viewers, but it’s an idea with a long history in conservative media. (Here’s a version from National Review, for example.) Many on the right argue that a better armed populace might have resisted the Nazis.

Why it matters (or doesn’t): Understandably, many people find this argument offensive, in part because it implies Jews didn’t do enough to defend themselves. Moreover, experts from historians to the Anti-Defamation League have rejected the idea as factually baseless. The gaffe also cements Carson’s penchant for poorly considered remarks—comparing the U.S. to Nazi Germany elsewhere, or likening ISIS to the Founding Fathers.

The moral: You know who else misinterpreted history to further his ideological goals?

The candidate: Ben Carson

The gaffe: Speaking to Marketplace, Carson revealed that he has no idea how the debt limit—a ceiling not on how much the government spends, but on whether it can borrow to pay off existing debts—functions. “Should the Congress then and the president not raise the debt limit? Should we default on our debt?” Kai Ryssdal asked. Carson replied: “Let me put it this way: if I were the president, I would not sign an increased budget. Absolutely would not do it. They would have to find a place to cut.” Ryssdal tried repeatedly to refocus Carson from spending to the debt limit, and Carson clearly didn’t understand the difference.

The defense: Carson is wrong, but he’s not alone. Most Americans don’t understand the debt ceiling. Moreover, while many Republicans saw brinksmanship on the debt limit as leverage against President Obama, others seemed to sincerely and incorrectly believe the nation wouldn’t default if it wasn’t raised—including Carson’s Republican rival Rand Paul.

Why it matters (or doesn’t): The president of the United States needs to understand the difference between the debt ceiling and the budget.

The moral: This stuff is a little complicated, but it ain’t brain surgery.

The candidate: Ben Carson

The gaffe: Asked by a radio interviewer whether he’d consider running as an independent, the Republican candidate seemed open. “If I had to, I would, but I don’t think it’s necessary,” Carson said, three times offering similar answers. The fourth, he insisted, “No, I didn’t say that at all. That’s not what I’m saying.” But Carson, like every other GOP candidate, has signed a pledge saying he wouldn’t run outside the party.

The defense: Look, no one believes those pledges are worth the paper on which they’re printed.

Why it matters (or doesn’t): In general, any candidate who can’t win a party’s nomination isn’t able to mount a serious third-party challenge anyway. (Sorry, John Anderson.) The weird exchange does speak to Carson’s occasional lack of verbal discipline, which has led him to awkward and strange statements before.

The moral: The loyalty pledge was intended to ensnare Trump, but what’s good for the goof isn’t necessarily good for the panderers.

The candidate: Jeb Bush

The gaffe: At an event near Charleston, South Carolina, a man noted the mostly white crowd and asked Bush how he’d win over and include black voters. “Our message is one of hope and aspiration,” Bush said. “It isn’t one of division, and get in line, and we’ll take care of you with free stuff. Our message is one that is uplifting—that says you can achieve earned success."

The defense: In 2012, Mitt Romney said, “I hope people understand this, your friends who like Obamacare, you remind them of this, if they want more stuff from government tell them to go vote for the other guy—more free stuff.” After the election, he said, “The president’s campaign focused on giving targeted groups a big gift.” At least Bush acknowledges there’s another way to win black voters.

Why it matters (or doesn’t): Even with that slight improvement, this isn’t good. (There’s a reason Romney’s comments were widely decried, including by Republicans.) First, it tells black voters that the patrician Bush thinks they vote Democrat mostly for giveaways, which is a bit insulting. Second, and more importantly, it reinforces a false idea that whites don’t receive federal-assistance “gifts”—a majority do. Third, it ignores the fact that tax cuts for high-earners, like the ones Bush has proposed, are very much “free stuff.” It turns out voters of all stripes like gifts!

The moral: It’s always better to give than receive, but it is essential to give if you wish to receive votes.

The candidate: Jeb! Bush

The “gaffe”: Bush in Iowa, as reported by Talking Points Memo: “We should not have a multicultural society. When you create pockets of isolation, and in some cases, the assimilation process has been retarded, it’s wrong. It limits people’s aspirations.”

The defense: This isn’t a gaffe, no matter what Jeet Heer says. Some folks were upset that Bush had used “retarded,” a no-longer-favored term for developmental disabilities. But the context in which he used it was the most basic, literal sense of the word: “slowed.” (Zack Beauchamp explores this at more length and is right on.)

Why it matters (or doesn’t): It doesn’t matter a whit to Bush. But this is a cautionary tale for a press that is all too often eager to spot and make hay of candidates’ “gaffes.”

The moral: He who declares a gaffe first, gaffes worst.

The candidate: still Donald Trump.

The gaffe: At an event in Rochester, New Hampshire, a man said this to Trump: “We have a problem in this country. It’s called Muslims. You know our current president is one. You know he’s not even an American …. Anyway, we have training camps growing where they want to kill us. That’s my question: When can we get rid of them?” Trump answered, in typically non-specific fashion, “We’re going to be looking at that and plenty of other things,” but didn’t contradict the idea that President Obama, an American-born Christian, is a non-American Muslim, nor did he disagree that Muslims are a problem.

The defense: The campaign says Trump just meant he’d look into getting rid of the alleged camps, not Muslims. But it’s hard to give the benefit of the doubt to a guy who loudly demanded Obama’s birth certificate in 2011 and in July suggested he still harbors questions about the president’s nationality.

Why it matters (or doesn’t): Declining to push back on these bigoted comments, and ratifying the birther premise, ought to be disqualifying. But everyone knows how previous “disqualifying” moments have hurt Trump: Not at all.

The moral: If the mountain won’t come to Muhammad, Muhammad should probably avoid the White Mountains.

The candidate: Mike Huckabee

The gaffe: In explaining why he supports Kim Davis and rejects the Supreme Court’s ruling in Obergefell, Huck reached way back: “The Dred Scott decision of 1857 still remains to this day the law of the land, which says that black people aren’t fully human. Does anybody still follow the Dred Scott Supreme Court decision?” Well, no—because it was overturned by the Fourteenth Amendment, in 1868.

The defense: Constitutional law is difficult, and the former Arkansas governor has struggled with it before—for example, advancing novel and nonsensical theories about how states could respond to the Supreme Court that echo historical “nullification” efforts.

Why it matters (or doesn’t): If you’re making a dubious states-rights-based claim, don’t cite the most infamous pro-slavery decision in American history.

The moral: Those who cannot remember the past are condemned to repeat foolish arguments about it during their presidential campaigns.