Voters are not Thinking like bankers. We're thinking like sports fans.

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% L