Berkeley, California, has long prided itself on being the most left-leaning city in the United States. Unmoored from the hierarchies and traditions of other parts of the country, the city stands strong on the left-most edge of progressive politics.

Back in the 1960s, it was a place where Black Panthers hawked Mao’s Little Red Book to students in the Free Speech Movement. It’s sometimes jokingly referred to as the “People’s Republic of Berkeley” – by residents, not Bill O’Reilly. In the 2016 Democratic primary, the city pulled hard for Bernie Sanders.

As “resistance” has become the rallying cry of the post-Trump left, Berkeley has, unsurprisingly, emerged as a hotbed of protest. But the resistors’ calls to action raise an obvious question: how?

Left-leaning Americans have called Congress, donated to the American Civil Liberties Union, tweeted angrily at Paul Ryan and plotted a Democratic comeback for 2018.

We’ve taken to the streets in record numbers. The Women’s March, which massively overshadowed Trump’s inauguration, brought us hand-knit pink hats, the burgeoning resistance’s first accoutrements. Since then, though, pink hats have been tucked away deep in drawers – and black masks have started becoming more visible.

In recent weeks, especially since the clashes in Berkeley last weekend, focus has shifted from benign protesters to the people in black fatigues belonging to the anti-fascist group Antifa.

Antifa is a collection of autonomous networks committed to anti-racism and anti-capitalism. Its adherents reject the state or police as a means to stop the violent speech, ideologies and actions of white supremacists and instead advocate popular direct action. Their tactics can include property destruction and violence. This, they say, is justified.

Fascists and white supremacists often show up looking for a fight, and protesters need to be protected when the police refuse to budge. In their view, entrenched systems of racial and economic oppression are not mere theoretical structures – they threaten people and can and should be opposed with force.

In the weeks after the election, a friend brought me to a meeting in Brooklyn organized by the Base Collective – a group many would now call Antifa.

The main ideas put forward in the meeting, as I recall, were that we must oppose fascism and racism by any means necessary, and protect immigrants and people of color from Immigration and Customs Enforcement and the police.

I almost added my email to their listserv out of curiosity but thought better of it. I worked for the city of New York at the time and am no anarchist, by any definition. I believe government has a responsibility to empower people and advance common goods including justice, equality and progress (a hard sell these days, I realize).

Still, having heard Antifa’s elevator pitch in person, I must acknowledge that their analysis of ingrained injustice gets more than a little bit right.

Corporate power ought to be challenged. Racial hierarchies are deep and powerful and must be uprooted. The criminal justice system perpetuates mass incarceration while doing little – or nothing – to address police violence.

States captured by corporate interests routinely run roughshod over democratic, Indigenous and local control of land, water and resources, as witnessed at Standing Rock. Ours has become a land of inequity and injustice aplenty.

But in their flirtation with political violence, Antifa ends up hurting the progressive groups it stands with and claims to protect.

They play into the cartoon-image of the left sketched by Fox News and Breitbart. Though violence may not be their dominant tactic, it is inevitably their hallmark. And though the group may not always incite violence, their presence invites it, putting others in danger.

Our resistance must be non-violent, through and through. We draw from a long line of non-violent organizing stretching from the Indigenous Maori Parihaka movement, which resisted confiscation of their lands in the 19th century, providing a model for Gandhi, the civil rights movement and Standing Rock. We stand proudly on these righteous shoulders.

Nonviolence is also empirically proven to be the most effective strategy for resistance. As award-winning research by political scientist Erica Chenoweth has shown, nonviolent movements have been more successful in removing autocratic leaders from power throughout modern history than violent ones.

Violent tactics, even if they are only deployed sparingly and defensively, undermine the resistance, damning progressive values of freedom, equality and justice by association. If Antifa stands for these values, as they claim, they must step aside. And while we show Antifa the door, I have one fashion suggestion: take the pink hats out of the drawer.