Note: This piece was first published in December 2015, in the wake of the San Bernadino shooting.

One thing I often hear in the wake of these endless mass shootings is, "Surely this will convince those gun people. Surely the carnage and suffering are bad enough now that they'll feel compelled to support some gun control."

This betrays a fundamental misunderstanding of the cognitive and emotional dynamics at work. It presumes that mass shootings constitute an argument against guns, to be weighed against arguments in their favor. But to gun enthusiasts, mass shootings are not arguments against guns but for them. The rise in mass shootings is only convincing both sides that they're right, causing them to dig in further.

It's not even clear that opinions on guns and gun violence remain amenable to argument. Over the past few decades, gun ownership in the US has evolved from a practical issue for rural homeowners and hunters to a kind of gesture of tribal solidarity, an act of defiance toward Obama, the left, and all the changes they represent. The gun lobby has become more hardened and uncompromising, pushing guns into schools, churches, and universities.

This has taken place in the context of a broader and deeper polarization of the country, as Red America and Blue America have become more ideologically homogeneous and distant from one another. The two sides are now composed of people who quite literally think and feel differently — and are less and less able to communicate. The gun issue is a salient example, but far from the only one.

This suggests that if the status quo on guns in the US is to change, it will be through overwhelming political force, not through evidence and argument. Guns have now ascended to the level of worldview and identity, areas largely beyond the reach of persuasion.

Conservatives are from Mars, liberals are from Venus

For years, an accumulating body of psychological and social scientific research has shown that, as Chris Mooney summarized in a 2014 article, "liberals and conservatives disagree about politics in part because they are different people at the level of personality, psychology, and even traits like physiology and genetics." (Mooney later gathered that research in his somewhat unfortunately titled book The Republican Brain.)

Mooney quotes psychologist John Jost and colleagues, writing in Behavioral and Brain Sciences:

There is by now evidence from a variety of laboratories around the world using a variety of methodological techniques leading to the virtually inescapable conclusion that the cognitive-motivational styles of leftists and rightists are quite different.

So, different how?

Jost and colleagues were responding positively to this paper by the University of Nebraska's John Hibbing, which argues, based on a series of experiments, that conservatives display a strong "negativity bias":

In this article, we argue that one organizing element of the many differences between liberals and conservatives is the nature of their physiological and psychological responses to features of the environment that are negative. Compared with liberals, conservatives tend to register greater physiological responses to such stimuli and also to devote more psychological resources to them.

Other research has traced this effect in part to the physiological level, finding that conservatives have larger right amygdalae. (The amygdala is a cluster of neurons in the brain's medial temporal lobe thought to regulate basic pleasure and fear responses; many psychological conditions, including anxiety and PTSD, have been traced to abnormal functioning of the amygdala.)

Heightened sensitivity to negative stimuli can mean a propensity for anxiety, fear, and occasionally alarm. If fear threatens loss of control, many traits common to conservatives can be seen as efforts to reassert control. As Jost and colleagues summarize: "Research consistently finds that conservatism is positively associated with heightened epistemic concerns for order, structure, closure, certainty, consistency, simplicity, and familiarity, as well as existential concerns such as perceptions of danger, sensitivity to threat, and death anxiety."

Another way of framing the differences is in terms of the five-factor model, a set of five core personality traits many psychologists use for assessment: openness to experience, conscientiousness, extraversion, agreeableness, and neuroticism.

As Mark Mellman wrote in 2015, liberals and conservatives consistently differ on a few of these traits. Liberals are more open to new experiences, novelty and disruption; conservatives prefer stability and the status quo. Liberals are more tolerant of mess, ambiguity, and uncertainty; conservatives prefer tidiness, clarity, and certainty.

Yet another way to frame the difference: Yale psychologist Dan Kahan, whose cultural cognition work Ezra has written about before, divides worldviews along two dimensions, hierarchical vs. egalitarian and individualist vs. communitarian. This creates a four-quadrant space; conservatives are hierarchical-individualists.

These differences can help inform our understanding of current US politics, but first we should head off a few misunderstandings.

Caveats about personality research

Talking about deep personality differences is a sensitive business and inevitably draws some anger. So it's worth clarifying a few things.

1) Everything is a spectrum and everyone is a unique snowflake

All these conservative tendencies put together and pushed to the extreme amount to authoritarianism. The liberal inverse amounts to a kind of drifting libertinism. In practice, very few people lie at the far ends of the bell-curve distribution. Most people are somewhere closer to the middle, an idiosyncratic mix.

What's more, different aspects of personality can be elicited by different circumstances, at different times, around different people. In times of peace and growth, there's a drift toward liberalism. Fear and crisis tend to push everyone the other direction, to shrink boundaries of concern and heighten in-group/out-group sensitivity. So liberal and conservative traits are not static, at the group level or within an individual.

Everyone is unique. No individual is predicted or explained by this research. These are general tendencies, heuristics, fluid and context-sensitive.

2) The research draws no value judgments

Whichever of these personality traits, or clusters of traits, you might prefer, the research itself does not characterize any as better or worse. It's easy to imagine circumstances in which sensitivity to threat and commitment to stability are valuable and others in which risk-taking and innovation are valuable. And it's likely valuable to have a mix, a balance, no matter the circumstances.

3) Liberal and conservative do not always map to political left and right

As Mooney is at pains to emphasize in his book, personality does not dictate ideology. There's no law of nature that conservatives are confined to the political right. The 20th century offers no shortage of authoritarian leftists. When the political left dominates the political order, those prone to defending the status quo will tend to be leftists.

There was a period in the mid-20th century US when liberals and conservatives were somewhat more evenly distributed across the parties — there were conservative Democrats and liberal Republicans. But the past four or five decades have seen a slow (lately accelerating) process of polarization. Americans have sorted themselves: Almost all liberals are now Democrats; almost all conservatives are now Republicans. In Congress, the leftmost Republican is to the right of the rightmost Democrat.

Guns have become a last-ditch effort to impose control on a world slipping away

Let us imagine, then, a conservative gun owner — an older white gentleman, let's say, in his 50s, living in the Rust Belt somewhere. When he was growing up, there was living memory of a familiar order: men working in honorable trade or manufacturing jobs, women tending home and children, Sundays at church, hard work yielding a steady rise up the ladder to a well-earned house, yard, and car.

That order was crumbling just as our gun owner inherited it. The honorable jobs are gone, or going. It's hell to find work, benefits are for shit, and there isn't much put aside for retirement. The kids are struggling with debt and low-paying jobs. They know, and our gun owner knows, that they probably aren't going to have a better life than he did — that the very core of the American promise has proven false for them, for the first time in generations.

It's a bitter, helpless feeling. And for someone naturally attuned to "order, structure, closure, certainty, consistency, simplicity, and familiarity," it's scary. The role he thought he was meant to play in the world, the privileges and respect that came along with it, have been thrown into doubt. Everything is shifting under his feet.

Over the last few years, our gun owner has found a whole network of TV channels, radio shows, books, blogs, and Facebook groups that speak directly to his unease. They understand the world he heard about from his father and grandfather, the world that's being lost; they understand the urgency of saving what's left of it.

Most of all, with his already heightened sensitivity to threat further aggravated by economic uncertainty, they finally help him see who's to blame. They show him the immigrants crowding in, using up jobs and benefits that were promised to American workers. They show him minorities demanding handouts that are paid for with his taxes, even as they riot, even as they kill each other and the police. They show him terrorists making a mockery of weak American leadership. They show him elitist liberals, professors and entertainers, disdaining his values and mocking his religion.

And it is such a relief, to finally put a face to all the ambient dread, to have some clarity again, to know who the good guys and bad guys are. Our gun owner is a good guy, thankfully, from the kind of self-reliant stock that settled this country.

It seems like America's decline is a done deal, that the tide of liberal rot is unstoppable. But the one place he knows he can draw the line is at his door, on his private property, because he has a gun. He can defend his own. If the minorities riot again, or immigrant criminals move in nearby, or terrorists attack, or some wackjob goes on a shooting spree, or Obama comes for his guns ... well, that's what the guns are for. He's given up a lot, but he won't give up his autonomy or the safety of his family. He'll defend that to the end.

To our gun owner, another mass shooting is not an argument for getting rid of guns. It's a confirmation of his every instinct, another sign of moral and societal decay, another reason to arm himself and defend what he's got left.

You can tell him about Canada and Australia until you're blue in the face — the lower rate of gun deaths, the hunting exemptions, the seemingly intact freedoms. You can cite high popular support for restrictions on gun and ammunition sales. You can tell him that not every incremental tightening of standards is a slippery slope, that no one wants to confiscate his guns.

But you're just another self-righteous liberal on another self-righteous crusade, too blind or stupid to see how governments always use people like you to disarm their citizenry. You've taken enough — of his taxes, his freedoms, his culture. He won't give you any more.

A cherished myth of American politics (indeed, of democracy generally) is that it's fundamentally about persuasion, the contest of ideas. But in a political system already biased against action, in which members of both parties are becoming more ideologically and even psychologically distant, persuasion on issues that activate tribal identities is all but impossible. Our gun owner is not going to change his mind; everything gun control proponents consider evidence for their side, he considers evidence for his. The differences run deeper than evidence.

If there are ever to be gun laws passed in the US, any kind of policy response to the rising tide of mass shootings, it will be because the people who want it amass the political power to overwhelm the power of the gun lobby. It will be because they organize and deploy more intensity, money, and votes than their opponents. More mass shootings are not going to do the job for them.

VIDEO: America's gun problem explained in 90 seconds