"I don't mind disavowing anybody," said Donald Trump, after he got in some trouble for disavowing, and then later not disavowing, notorious white supremacist and former KKK leader David Duke, who is an enthusiastic supporter of his. On the other hand, "I'm saying to myself, how many times do I have to continue to disavow people?"

It's a question other candidates have surely asked themselves before. Hillary Clinton, for instance, is now being asked to disavow the 1994 crime bill signed by her husband, and the word "superpredator," which she used at the time (she disavows the latter; on the former, it's complicated). Bernie Sanders hasn't been asked for any disavowals yet, but after a lifetime in leftist politics, if he becomes the Democratic nominee, you can bet there are opposition research books full of associations he'll be asked to disavow.

If they're successful, any presidential candidate is going to have to disavow somebody at least a few times before the election. Sometimes it's an endorsement you'd rather not have gotten, sometimes it's somebody whose support you wanted but who then went a little crazy, and sometimes it's a group or an idea that others might, absent a disavowal, associate with you. Sometimes the disavowal game gets a little ridiculous, for sure, but there's a legitimate public service behind the "gotcha."

What's the point of the disavowal ritual? Much of the time it's driven by a candidate's opponent looking to put them on the defensive; in that way it's just another form of the feigned outrage that occupies half our time in every campaign. Sometimes it comes from the media, which always likes to watch candidates squirm. But its real purpose is to define the boundaries of the acceptable, both within each party and in politics as a whole. When someone gets disavowed, we all know that to be associated with them will lead to shame and reproach. That person and what they represent, it has been made clear, is out of bounds. So Donald Trump can say Mexicans are rapists and we should keep Muslims out of our country, and he'll be punished with some strongly-worded opinion columns. But an endorsement from David Duke requires a disavowal.

Like many rituals, it often requires the incantation of specific words, particularly "I disavow…." If you don't say that, some enterprising reporter will ask, "You've said you disagree with and reject that person, but do you disavow him?" Until the words are spoken, the ritual is incomplete and the candidate can still be suspected of harboring sympathies for the person or group we've collectively decided is beyond the pale.

But underneath the sometimes silly enactment of the disavowal ritual there lies a worthwhile search for understanding. We're talking about the people who would be president, and even though we know a good deal about them, it's important to know who they'll surround themselves with, even if they can't be responsible for everyone who tries to attach themselves to the candidate or the president. When they assume office, presidents carry with them an enormous constellation of people. There's the staff, of which there are thousands throughout the federal government. There are the political allies inside government, particularly members of Congress. Then there are the interest groups, the lobbyists, the supporters, and everyone else who might exercise some influence over the person in the Oval Office. There are those who offer their private counsel and those who agitate from without. We should try to understand as best we can who all those people are, and how much sway they might have.

Disavowals don't usually enable us to do that, since they tend to focus on the outliers, not those who are likely to be close to the president. I seriously doubt that even if Donald Trump were president and American society plunged into a harrowing post-apocalyptic nightmare of madness, chaos, and despair, that David Duke would be able to call up the White House and get Trump on the phone.

So why do we insist that Trump disavow Duke? If Duke endorsed Hillary Clinton, she would just say, "That's bizarre," and no one would demand a disavowal. That's because no one believes that David Duke has anything to do with her views or what kind of president she'd be. But it's precisely because Trump has based so much of his campaign on ugly nationalism that when Duke offers his endorsement, we actually have to ask Trump to be clear. And while no one gets asked to disavow people and ideas more often than Trump, that's because he's the only one retweeting bon mots from neo-Nazis and entertaining every bizarre conspiracy theory that comes his way.

Every once in a while, a politician breaks out of the disavowal ritual. That's what Barack Obama did in 2008, when he was asked to disavow his former minister, Jeremiah Wright. Obama gave a speech in which he tried to explore everyone's complex and often less-than-admirable emotions on the subject of race. Though he used the word "disown" instead of "disavow," Obama refused to perform the ritual in the way it had been prescribed. "I can no more disown [Reverend Wright] than I can disown the black community," he said. "I can no more disown him than I can disown my white grandmother — a woman who helped raise me, a woman who sacrificed again and again for me, a woman who loves me as much as she loves anything in this world, but a woman who once confessed her fear of black men who passed her by on the street, and who on more than one occasion has uttered racial or ethnic stereotypes that made me cringe."

In other words, when it came to that call for disavowal, Obama insisted that things weren't so simple. But David Duke? That one ought to be easy.