We've heard a lot in this election cycle about the idea of party "establishments" and "establishment candidates." I've used this term plenty of times, often in reference to the split within the Republican Party between insurgents and "establishment types." But I've always had a nagging feeling that I wasn't doing a very good job laying out what that distinction means. This seems like as good a time as any to try to untangle the concept and figure out whether it's really helpful for analyzing party politics.

There's actually a whole political science literature about concepts. I won't delve too deeply into it here, but there's one key idea that's common in most of the writing about concepts, from Giovanni Sartori's classic article to more contemporary work like this piece by John Gerring. It's the idea that we shouldn't reconfigure our concepts to fit new or strange cases, adding criteria that aren't obviously related to the core definition of the concept or that obscure its meaning.

It seems to me that this is happening to some extent as we try to figure out what's going on in the Republican nomination race. You frequently hear people refer to the "establishment lane" as a distinct group of candidates. And it's not too hard to figure out that Jeb Bush, John Kasich, and Marco Rubio are in that group, while Donald Trump and Ben Carson are not. What about Carly Fiorina, who has run for office on the Republican ticket before?

And then there's the most confounding example: Ted Cruz. Other Republican elites don't seem to like him very much at all, and he obviously belongs to an ideological movement within the party. But can we really say that a sitting senator is not an establishment candidate?

If we decide that the defining feature of being an establishment candidate is the approval of the establishment, then we are faced with a bunch more questions. First, who is part of the party establishment? Second, this make us reconsider Kasich, widely acknowledged after each debate to be very different in tone and orientation from many of the other candidates. Despite his endorsement from that venerated mouthpiece of conservatism, the New York Times, Kasich lags in endorsements from Republican officeholders. It's easy to use "establishment" as a label to distinguish Bush from Trump, or even Hillary Clinton from Bernie Sanders (though I think the senator caveat applies there, as well), but the concept fails us when we really need it —to tell us something meaningful about the candidates who don't fit either mold.

Another problem is that the idea of party establishment doesn't seem to mean the same thing in both parties. Let's think about Clinton versus Sanders for a moment. Clinton's dominance in the endorsement primary certainly clarifies her establishment credentials. But when people use that label to distinguish her from Sanders, it's also about issue positions. Specifically, Sanders is more economically liberal than Clinton, and a lot of his appeals against her involve her connections to Wall Street and powerful financial interests.

In other words, the establishment label refers to relative ideological moderation and lack of interest in challenging powerful institutions. Writing in Politico, Jack Shafer takes this even further, suggesting that, "the Establishment cares more about its own continuance than it does its ideology."

On the Republican side, I think the presumption that establishment candidates are more moderate is also common, but it's less clear that it's an accurate representation of their ideology. The battle among Republican candidates also reveals a struggle within the party not over who is the most conservative, but rather over what conservatism means in the first place. Contemporary conservatism also has an anti-party, anti-authority strain embodied by libertarian types like Rand (and Ron) Paul and by conservative populists like Sarah Palin and Trump.

The prominence of the anti-authority strain in conservative politics means actors who command certain kinds of power over the party are sometimes only loosely affiliated with the formal hierarchy. The idea that there is no Republican establishment — that elite and outsider statuses are too often mixed or inverted, or that elites are fragmented — has been a recurring trope for years. But repeating it doesn't give us any more of an idea of what, exactly, we are missing if that claim is true.

In other words, in both parties there's a qualitative dimension to the establishment idea that doesn't perfectly map onto left-right ideology. But I think it's a more obvious extension of ideological positioning for Democrats than for Republicans. So if we mean ideological moderation, we should just say that. And if we mean elites — officeholders, leaders of interest groups, and prominent members of the media — we should just say that, and contrast it with non-elites: ordinary voters, citizens, party rank and file. When describing candidates, it might be better to distinguish along clear criteria: endorsements or whether the candidate has held elective office. What we lose in description, we gain in clarity.

Using the establishment label for candidates not only fails to help us define hard cases, it also obscures a crucial distinction among candidates. Candidates like Sanders and even Cruz (who doesn't seem to have made too many friends in the Senate) are connected with larger movements. For Cruz, it's the Tea Party, which mainly functions within the Republican Party; for Sanders, it's a larger movement around economic inequality that includes Democratic activists but also others outside the party.

In 1976, when Ronald Reagan ran as an insurgent, he had the backing of a growing conservative movement. Trump, though a rare candidate in this regard, deserves a different label. He's not part of an insurgent movement; his ideas are centered on him, the candidate. The movements that Cruz and Sanders represent may well become the "establishment" ideas of their respective parties — the Tea Party probably already has. But for Trump, there's little chance of that happening because there's no organized movement there. The tools to sustain demagoguery are better than they have ever been — social media, mass communication, and travel. And clearly Trump's message resonates with a larger number of citizens than many of us predicted.

In 2011, Thomas Friedman wrote of Americans Elect, a movement to nominate a centrist candidate through a web-based voting process, that the "internet would to do politics what Amazon.com did to books." That is, render parties obsolete just like brick-and-mortar bookstores. (Apparently Amazon is building some stores, but that's another matter entirely). Americans Elect never went anywhere. But Trump's brand of conservative populism is what party-free politics really looks like.

Who makes up a candidate's support coalition matters — the resources, interests, and networks. Sanders's supporters and donors are different from Clinton's — although, again, this distinction is much cleaner on the Democratic side this year. But most movements constrain the ideas and ambition of the candidates they support. They cultivate other leaders, they form coalitions, and they guard their collective reputations. The absence of these connections is a crucial element of insurgent candidacies like Trump's. However we define our concepts, that dimension should be front and center.