Political scientist Lilliana Mason on social sorting, partisan self-deception, and why the two-party system makes all of it worse.

The latest episode of This Old Democracy features the remarkable Lilliana Mason, a professor of political science at Johns Hopkins, in a wide-ranging conversation with host Micah Sifry.

Mason offers a rigorous — and at times unsettling — account of why Americans have stopped thinking of their political opponents as fellow citizens. She discusses parties, politics, policy, and young people. We really need to think about this one because the civil in civil society is an essential piece of the democratic puzzle.

In Mason’s view, political parties are essential to democratic decisionmaking.

“[Parties] are a really useful informational shortcut for us. We can’t ask our citizens to read every single piece of legislation and every piece of the party platform and know about all of the different parts of the platform and fully understand these policies. The reason we have representative democracy is because we don’t all have time to do that and we can’t expect everyone to do that. And so what parties do is they simplify that political decision that we are given the privilege of making as citizens. We can’t all be experts. And so the parties give us a much simpler choice.”

Mason’s work centers on a deceptively simple insight: we don’t really choose our political parties the way we choose between competing products on a shelf. The “banker mind” model of democratic citizenship — the idea that voters coolly weigh policy options, calculate trade-offs, and select the candidate who best serves their interests — is, she argues, largely a myth. The reality is considerably messier.

“Our punditry tends to assume that we think about politics sort of like bankers and we’re choosing investments with a sober and quantitative mind and assessing the positives and negatives, you know, is this policy marginally affecting my family in this number of decimal points? But actually, that’s not how we participate in politics. We’re much more like sports fans when we engage in politics.”

What has happened over the past six decades, Mason explains, is a process she calls social sorting: the gradual alignment of partisan identity with race, religion, geography, and other social identities. In the 1950s, both parties contained meaningful internal diversity — cross-cutting coalitions that made it impossible to know, just from someone’s party registration, very much about who they were. That era is over. Today, the parties have sorted themselves into two fairly coherent tribes, and the sorting makes genuine cross-partisan contact rarer with every passing election cycle.

What makes social sorting especially durable, Mason says, is that people genuinely believe they are reasoning independently — even when they’re not. She describes a political science experiment in which subjects were randomly assigned either a Democratic or Republican label to the same welfare policy. Democrats reliably preferred the “Democratic” policy, and Republicans the “Republican” one, even when the substantive details of the policies had been swapped. When asked afterward whether their party had influenced their preference:

“Everyone said, not at all. That was entirely me. I have entirely come up with the reasons for my desire to have this policy enacted. We don’t know that we’re doing it. And also in that experiment, they said, do you think other people are influenced by their party? And everybody says, yes, definitely. Everyone else is influenced by their party, but I’m not.”

The distortions don’t stop at policy preferences. Mason’s research also documents systematic misperceptions of who actually belongs to each party. Americans consistently overestimate the share of Democrats who are Black, LGBTQ+, or non-Christian — and overestimate the share of Republicans who are elderly or evangelical.

“Most people assume that Democrats are 35% LGBT and the true number is 5%. They assume that Democrats are 40% Black and the true number is 25%.”

These stereotypes aren’t merely factual errors. They shape the emotional valence of partisan identity: if you believe the other party is almost entirely composed of groups you view negatively, your hostility toward that party will track your feelings about those groups — whether or not the factual premise is accurate.

The stakes of all this, Mason makes clear, are not merely rhetorical. In her book, Radical American Partisanship, she and Nathan Kalmoe measure the kinds of attitudes that social scientists have found to precede mass violence in other contexts — dehumanization, vilification, openness to political aggression. The numbers they’ve compiled since 2017 are worth sitting with:

“In 2017, it was about 40% of Democrats and Republicans who were willing to say the other party was evil. It’s gone up to almost 70% of Republicans in 2022. Last summer, it’s around 50 to 60% of Republicans and Democrats. In terms of dehumanizing the other side — we’re up to 40% of Democrats and Republicans who are willing to say that people in the other party don’t deserve to be treated like humans because they behave like animals.”

Mason is careful not to predict catastrophe, but she is equally careful not to minimize the data. The nightmare scenario, she says, is a tit-for-tat cycle: roughly 20% of Americans say violence to achieve political goals might be justified — but when asked what they’d do if the other side starts it, that number climbs to 40, 50, sometimes 60%.

Sifry asked Mason about the degree to which the two-party system itself is accelerating these dynamics. Her answer was unambiguous:

“The two-party system is a huge part of this. There’s a psychological reason for that, which is that when you have a perception of a zero-sum competition, then the competition is more intense. Either we win or we lose. And the people who benefit from our loss are always the same people.”

Mason explained that In multi-party systems, by contrast, the lines of “us” and “them” are inherently more fluid. Parties that are adversaries in one election may be coalition partners in the next; voters have in their living memory experiences of that fluidity. Research comparing “affective polarization” — the raw emotional dislike of partisan outgroups — across democracies has found it to be less intense in systems where coalitional politics are the norm.

The problem in the United States, Mason notes, is institutional: the two-party structure is deeply embedded in the rules of how we run elections. Dismantling it requires creativity — precisely the kind of creativity that efforts to revive fusion voting and open up the ballot are attempting.

On the question of democratic restoration, Mason offers two distinct registers of hope. The first is structural and long-term: fixing the institutional incentives that make our current polarization rational from each party’s perspective. The second is personal and immediate: recognizing that norms — unlike laws — are enforced socially rather than by state power. Which means ordinary citizens have more agency than they might think.

“If we don’t like the behavior that we’re seeing from our political leadership, we ourselves enforce the social norms around politics. And if we feel like politics is getting too nasty and rude and uncivil, then one thing we can do is model good behavior, discourage bad behavior, and be the people that we wish our leaders were being.”

Asked how she personally copes with staring daily into the abyss of American partisan hostility, Mason offers a warmer note. She reads fiction before bed. She teaches college students. And she finds something genuinely encouraging in the generation that has never known a political moment before Trump:

“This young generation — they don’t remember a time before Trump. And they are pretty disgusted with the way they see the adults behaving right now. And they want a different kind of politics… They’re creative, they’re interested, they’re paying a lot of attention, and they want something better.”

RECOMMENDED READING

Liiliana Mason’s books include:

Uncivil Agreement: How Politics Became Our Identity

and

Radical American Partisanship: Mapping Violent Hostility, Its Causes, and the Consequences for Democracy (with Nathan Kalmoe)