One of the perennial debates in politics is over the role of radicals — activists with positions and demands outside the current mainstream. Think hard drug legalizers, advocates for a universal basic income, or, on the right, those who want to repeal the 17th Amendment. (Yes, this is a thing on the right now.)

Time to repeal 17th Amendment. Founders had it right-Senators chosen by state legislatures. Will work for their states and respect 10th amid — Gov. Mike Huckabee (@GovMikeHuckabee) July 28, 2017

The question can be boiled down to this: When a radical faction makes extreme policy demands, what effect does it have on the larger policy debate?

Does it discredit the moderates on the same side, by association? Or does it legitimate them, by contrast? Do advocates for cocaine legalization tarnish advocates for marijuana legalization, by making “legalization” in general seem radical? Or do they have the effect of making marijuana legalization seem like the safe, centrist choice?

Based on their behavior, the two US political parties have different answers to these questions.

The hard-right conservative movement that began building in the 1960s has now entirely colonized the GOP. Right-wing media, which has no incentive to compromise and every incentive to stoke outrage, is in the driver’s seat. The imperative for Republican politicians, most of whom come from safe seats, is to satisfy their radicals, lest they face a primary challenge.

The left has always been more wary of its activists. The relationship between the party and the left end of the spectrum is notoriously contentious, as was rehearsed repeatedly throughout the Obama years and yet again in the 2016 primary.

Part of that is the corrosive effect of big money on the party establishment. Part of it is cultural and temperamental; Dem voters look more kindly on compromise and Dem elites venerate technocratic expertise. And part of it is structural. The left has to stitch together a much broader and more diverse coalition than the right to win — more a collection of interest groups, discrete voting blocs, than a coherent ideological movement. The Democratic Party has always had to rein itself in to hold onto moderates and balance the demands of competing factions. And since its activists tend to be more siloed than the right’s, they are less organized and exert less collective power.

The latest chapter of this drama is playing out right now, as the left pushes single-payer health care. Will pulling Dem politicians onto that bandwagon get them all dismissed as socialist? Or will it strengthen the hand of moderates who want to, say, lower the age of eligibility for Medicare?

As it happens, social scientists have studied this stuff. They call the effects of radicals on the debate “radical flank effects.” A negative radical flank effect is when radicals tarnish and discredit moderates by association. A positive radical flank effect is when radicals strengthen the bargaining position of core actors in their broader coalition.

A new paper, forthcoming in the journal Organization & Environment, takes a fresh look at this dynamic in the context of the climate movement. Specifically, it seeks to chart the effects that Bill McKibben, his organization 350.org, and their campaign to get big institutions to divest from fossil fuels have had on the public climate change debate.

(Update, November 17: The New York Times reports that Norway’s $1 trillion sovereign wealth fund may divest in international petroleum companies in what is “potentially the biggest advance yet for [350.org’s] global fossil-fuel divestment campaign.”)

Is there a McKibben Effect — a radical flank effect on the US climate debate? And is it positive or negative?

Thanks, McKibben

Todd Schifeling (of Temple University) and Andrew John Hoffman (of University of Michigan) set out to examine this question empirically.

Their starting point is that much research has been done on the direct interactions of activist interest groups and business/academic/political groups, but much less has been done on the indirect effects of radical flanking. It may be that a radical campaign does not succeed at achieving its own stated goals, but causes important shifts elsewhere in the debate.

This, more or less, is what they speculate is true of McKibben/350.org’s divestment campaign. Shortly after the 2010 midterms, students began advocating that their universities divest from investments in fossil fuels. McKibben and 350 took up the charge and popularized it, to the point that, as of today, 749 institutions are participating, worth about $5.53 trillion in investments.

Schifeling and Hoffman acknowledge that the divestment movement has not — and, realistically, probably cannot — accomplish its goal of substantially affecting the financial health of large fossil fuel companies.

But that was not its only aim. It also set out to remove the “social license” of fossil fuel companies to operate, to cast them as moral outlaws like cigarette makers. And it was paired, in 2012, with McKibben’s widely read “Global Warming’s Terrifying New Math,” which made clear that the vast bulk of existing fossil fuel reserves could not be developed in a climate-safe world — that fossil fuel companies’ interests were at odds with humanity’s interests.

On Earth Day, revisit our 2012 feature on global warming's terrifying new math: http://t.co/zHQGn8FbDy #longreads pic.twitter.com/dsWKTJQ2j5 — Rolling Stone (@RollingStone) April 22, 2015

To measure the indirect effects of that radical framing, Schifeling and Hoffman compiled an enormous database of newspaper stories about climate change published between 2011 and 2015. Using software wizardry (uh, details in the paper), they analyze the stories in three steps.

First, they look for the rise of mentions of the radical flank — the actors (McKibben and 350) and their policy demand (divestment). Second, they look at the process by which the demand becomes dissociated from the actors and enters mainstream dialogue. And third, they look at other changes in the structure of the debate.

I don’t pretend to understand the statistical tools involved — they produce something called “eigenvectors,” which is fun — but here’s how the authors sum up what they found:

Prior to the second half of 2012, conservative and liberal issues share a moderate level of centrality, while the radical flank occupies a more peripheral position. Transitioning from 2012 into 2013, the radical flank and liberal issues rise dramatically to dominate the network. Despite a slump from 2014 Q4 to 2015 Q2, these two groups hold a more elevated place in the network throughout the remainder of the time period.

The “conservative” position (more on that in a second) is “deny everything, do nothing.” As McKibben’s radical ideas pushed their way in, they carried liberal ideas (carbon taxes, cap-and-trade, clean energy subsidies, etc.) to the center of the debate along with them. The conservative position got crowded out, at least partially.

The radical position of divestment helped recenter the US climate debate around alternative solutions (rather than “do nothing” versus “do something”) in an enduring way — or at least enduring so far (more on that in a second too).

That’s pretty much the definition of a positive radical flank effect.

Why some radical flank efforts work and some don’t

The key question, obviously, is why some radical flank effects are positive and some are negative.

Schifeling and Hoffman get at this a little bit with a comparison of divestment to Naomi Klein’s book This Changes Everything: Capitalism vs. the Climate, which came out in 2014 and was similarly radical, but had much less effect on the larger debate.

Why is that? They propose a possible answer: The radicalism must be close enough to mainstream views to be bridgeable. Klein’s direct assault on capitalism was a bridge too far — there was no way to translate it into terms that could be adopted beyond the radical flank.

Here, divestment and “terrifying math” had a key advantage. Mainstream institutions were able to translate them into the language of stranded assets, a “carbon bubble,” and shareholder risk — terms the business community could understand and process. “Although it may be too early to tell,” Schifeling and Hoffman write, “a similar act of translation would seem unlikely for Klein’s anti-capitalism message.”

They don’t do too much with this idea, but I find it quite intriguing. It suggests that the key to success for radicals is to consciously find avenues through which their ideas can be dissociated from them and enter the mainstream.

The right has been extremely effective in this regard. They have a whole infrastructure of think tanks, media outlets, and advocacy groups designed to shuttle ideas from the fringe to the mainstream of the GOP. (Climate denial is but one of many examples.) If anything, that voyage has become altogether too short and easy on the right.

But the left’s infrastructure is less developed in that regard. There’s less cooperation, less synchronization, between activists and the mainstream. This paper suggests that the left should study the hand-off, the transfer, through which divestment and “leave it in the ground” came to be a lecture from the Bank of England on stranded carbon assets.

There is much to learn. (For instance, how might “100 percent renewable energy” follow a similar path?)

Two important caveats

It would be irresponsible to leave this study behind without noting two key caveats.

First, the US debate on climate change is unusual.

The assignment of these issues to ideological positions was specific to the climate change debate in the U.S., where the conservative position was anchored in denial, the liberal position was associated with policy response, and the emergent radical position called for the abolition of fossil fuels.

That is not the landscape of debate in most countries. The US Republican Party is the only major political party in the developed world that denies climate change — and rejects all attempts at solutions — as a matter of party orthodoxy.

That “do something, anything” is coded as the “liberal” position is a function of the lopsided US debate. “Keep it in the ground” is radical anywhere, but it appears unusually radical in the US, because the Republican Party is nuts.

Second, this is a fairly short-term study: 2011 to 2015. You might have noticed that US political circumstances changed quite radically in 2016.

Going forward, it will be important to see whether progress in the public debate reverts to its state prior to the radical flank or whether changes persist and moderate any attempts to reverse U.S. climate policy.

Yes, that will indeed be important! The American body politic may worry less about climate change as the chances of, say, a nuclear exchange with North Korea rise. As yet, is unclear how much the US climate debate has really advanced and how much it, like so many other American norms and debates, will collapse in the face of Trumpian chaos.

Early signs are positive, with cities and states rising to fill the federal gap. But if the last year has taught us anything, it’s that predictions are futile in the face of resurgent irrationalism and illiberalism. It remains to be seen whether the McKibben effect endures.