Hillary Clinton recently caught pneumonia, which would be a fairly unremarkable fact if dark tales about her health had not circulated among conservatives for years. Naturally it prompted another round of loopy speculation, highlighting yet again one of the more striking developments in US politics in the Obama era: the increasing prominence of conspiracy theories on the right.

Dark conspiracies have always been a part of politics, of course, on both sides of the aisle (see: 9/11 truthers). But since Obama was elected, conservative media and activists have pushed the right's conspiracy theories squarely into the mainstream of the party. Obama is a secret Muslim, he's planning a coup in Jade Helm, he tried to nuke Charleston, SC (seriously) ... the list could go on and on. Turn on a conservative talk radio show and there's probably a new one floating around as we speak.

Last year, Matt Yglesias flagged this quote from Ryan Lizza's great story on the turmoil in the Republican House. It's worth reading again:

"I used to spend ninety per cent of my constituent response time on people who call, e-mail, or send a letter, such as, ‘I really like this bill, H.R. 123,’ and they really believe in it because they heard about it through one of the groups that they belong to, but their view was based on actual legislation," [House Intelligence Committee chair Devin] Nunes said. "Ten per cent were about ‘Chemtrails from airplanes are poisoning me’ to every other conspiracy theory that’s out there. And that has essentially flipped on its head." The overwhelming majority of his constituent mail is now about the far-out ideas, and only a small portion is "based on something that is mostly true." He added, "It’s dramatically changed politics and politicians, and what they’re doing."

We don't need Nunes to tell us this, of course. Anyone who has followed political media over the past eight years has seen more and more conspiracy theories that would once have been confined to the John Birch Society fringe push their way into the mainstream political dialogue. Even on issues where Republicans believe they have a serious case for wrongdoing — Benghazi, Solyndra, Fast & Furious — the GOP has difficulty keeping serious investigations from getting bogged down and trivialized by conspiracies.

In the popular imagination, conspiracy theories are the result of ignorance and psychological instability. But it turns out that's not really true at all. Conspiracy theories are extremely common, even among well-educated, productive members of society. Some new research in political science helps home in on the circumstances and character traits that allow conspiracy theories to flourish — and casts a fairly grim light on the direction of American politics.

A study identifies the sorts of people susceptible to conspiracy theories

A Nov. 2015 study by political scientists Joanne Miller, Kyle Saunders, and Christina Farhart helps shed some light on these questions.

Endorsing conspiracy theories, they say, is a form of "motivated reasoning" — an effort to gather facts and construct frameworks that "protect or bolster one’s political worldview." They set out to determine what sorts of people are most likely to be susceptible to that sort of thing.

They went into the study with two hypotheses:

All things being equal, knowledge — close engagement with partisan politics, consumption of political news — will tend to exacerbate the tendency to endorse conspiracy theories (CTs). Trust in the political system will tend to mitigate this effect; those with high levels of trust will be less prone to accept CTs.

Putting those together, they expected to find CTs most common among high-information, low-trust people — those who are highly engaged and informed about politics but do not trust politicians, political elites, or mainstream institutions.

So do the hypotheses hold up?

The researchers found, after examining two large data sets (details in the paper), that the effect of trust is as expected, across the political spectrum. Lower-trust conservatives and liberals are both more likely to endorse ideologically congenial CTs (i.e., CTs that make the other side look bad).

But beyond that, there are interesting asymmetries. For liberals, more knowledge reduces endorsement of CTs, no matter the level of trust, and more trust reduces endorsement of CTs, no matter the level of knowledge — "knowledge and trust are both independently negatively related to liberals’ endorsement of liberal conspiracies."

For conservatives, on the other hand, more knowledge increases endorsement of CTs among those with low trust; for high-trust conservatives, knowledge seems to have no effect — it neither increases nor decreases tendency to endorse CTs.

In other words, the high-info/low-trust dynamic is in fact the conspiracy theory sweet spot, but primarily for conservatives.

What explains this asymmetry?

As the researchers say, their results are consistent with the theory "that conspiracy endorsement, and science denial more generally, is a more attractive worldview-bolstering strategy for conservatives than liberals, especially for high-knowledge and low-trust conservatives." That lines up with several other recent lines of research.

However, they are careful to acknowledge that there are alternative explanations for the asymmetry that they cannot (yet) rule out. Perhaps conservative conspiracy theories are simply easier to believe. Perhaps they are more salient at the moment (liberal CTs mostly date back to the Bush era). Perhaps the fact that there is a Democratic president in office has made conservatives more prone to CTs, and the effect would be reversed under a Republican president. Perhaps conservatives are just taking their cues from elites, who are more likely to push CTs when a Democrat is in power.

Why Republican politics have drifted toward conspiracies

Now. These researchers are admirable in refusing to draw conclusions beyond their data. But this is a blog post, not an academic paper, so I think it's okay for us to speculate a little further.

First, it's pretty obvious that conservatives are less likely than liberals to trust the political system. It's built into the ideology. What's more, conservative anti-government, anti-establishment sentiment has become more and more virulent over the past several decades. This lack of trust is not only directed at Democrats; the conservative base tends to scorn all professional politicians, including those in the Republican establishment.

Declining trust in institutions is a broader phenomenon in the US, of course, not confined to any political persuasion. But it is not symmetrical. Low trust has become endemic in American conservatism, not only when a Democrat holds the presidency, but generally. Thus the rise of Trump and other "outsider" candidates.

What's more, the conservative base is, relative to the broader electorate, more politically engaged and intense, which means its members are likely to pay more attention and have more knowledge (or at least "knowledge") about political events. By contrast, many of the demographics that make up the unwieldy left coalition are somewhat disengaged, less likely to consume partisan media, donate to candidates, or even vote.

What this suggests to me is that the prevalence of CTs among conservatives is not a temporary phenomenon, tied to Obama's presidency (or Trump's candidacy), but the result of deeper, longer-term social and demographic trends. Low-trust, high-knowledge conservatives are a breeding ground for CTs, and more and more conservatives are low trust and high knowledge.

(Side note: Liberals often want to dismiss the Tea Party as ignorant hicks, but demographic data shows that Tea Partiers are in fact higher income and higher education than the average voter or the average Republican.)

Is there any way to stop the spiral toward mistrust and conspiracies?

There are some horrible incentive structures built into current conservative politics. Conservative media, activists, and politicians have every reason to convince their most engaged supporters that the whole system is rotten and can't be trusted — it makes it easier to fill their heads with nonsense about Sharia law, Agenda 21, and all the rest, which in turn increases their intensity and engagement.

The researchers put it this way:

[C]onservative politicians and pundits can more readily rely on conspiracies as an effective means to activate their base than liberals. And to the extent that ideologically motivated endorsement is most evident among the least trusting of the knowledgeable conservatives, there is all the more incentive for conservative elites to stoke the fires of distrust.

But as we've seen, if that process goes on long enough, it produces two unpleasant results. First, the most engaged conservative voters will be more and more adrift in a paranoid fantasia, wrapped in an epistemic bubble filled with conspiracy theories, hassling politicians about them and making it effectively impossible for lawmakers to do their job in a reasonable way, as Nunes pointed out.

And second, they won't trust conservative elites any more than they trust liberals, scientists, or the media. That means they are not only deluded but unchecked, beyond the influence of any moderating force, easy prey for demagogues and hucksters. They become the conspiracy-addled tail that wags the political dog.

And that's exactly what we're seeing unfold on the right. Low-trust, high-knowledge conservatives — a.k.a. the conservative base — are bending the political system to their will on the basis of fever dreams that neither the media nor politicians can afford to ignore. Lacking the language or institutional means to dismiss popular conspiracy theories for what they are, feckless US political and media elites are instead normalizing them, "defining deviancy down" as the old phrase goes.

The research suggests that there is only one way to mitigate or reverse this process: restore some level of trust in the US political system. But conservative elites — who have the ear of their base — have no incentive to do so, and it's not clear that anyone else has ability to do so. Declining trust in institutions is broad and deep in America; it may very well be unstoppable. As long as it continues, conspiracy theories will play a larger and larger role in public life.

Cass Sunstein describes how conspiracy theories work