We tend to think of trust as something that grows where people agree. Where neighbors share values, where voters share a party, where a city sees itself as forward-looking and inclusive. The more common ground, the more trust. That, at least, is the intuition.

San Francisco complicates that picture. Eighty per cent of voters belong to the same party. Almost everyone calls themselves progressive. The city is wealthy, diverse, and proud of both. And yet, by one well-known measure, it is also among the least trusting cities in the United States. The deepest political conflicts are no longer between left and right. They run between people who all believe they are on the same side.

Our guest today has spent years thinking about why. She grew up in a modest stucco house beneath Sutro Tower, watched her neighborhood empty out in what was later named "white flight", and went on to become a political theorist. Her current book project asks the mirror image of the famous question Thomas Frank posed about Kansas. Not what is the matter with the American right, but what is the matter with the American left, and what San Francisco, as its laboratory, reveals about the limits of progressive politics.

She identifies four kinds of leftists in the city, traces the school board recall and the Chesa Boudin recall to something deeper than pandemic frustration, and reaches back to a nineteenth-century French idea - solidarism - for a way out. Her argument about trust is unusual: that distrust, the willingness to challenge entrenched power, is sometimes what makes genuine trust possible later on.

Our guest is Margaret Kohn, Professor of Political Science at the University of Toronto, and the author of the forthcoming book What's the Matter with San Francisco?