On the day of Donald Trump’s inauguration, Richard Spencer, a polemic thought leader in the racist “alt-right,” was punched in the face by a masked protestor. The moment was caught on video, and the punch quickly went viral on Twitter (sometimes set to music like Bruce Springsteen’s “Born in the USA”).

While it may not be accurate to call Spencer a Nazi—though he has called for “peaceful ethnic cleansing”—many online used the opportunity as thought experiment made-real: is it ever okay to punch a Nazi? What are the ethical arguments in favor and against physically assaulting people with truly repugnant opinions or beliefs?

In an op-ed for The Guardian, Tauriq Moosa, a blogger on common ethics, wrote a long piece framing the situation, explaining that:

“When a rule is worth following, it becomes “good”. This is why many agree “violence is bad” is a moral rule: it can be applied universally. Where rule-based morality runs into problems is when two moral rules conflict.

In this case, a rule we support is: “stopping Nazism is good”. Another is: “violence is bad”. This returns us to a dilemma instead of solving it.”

The inimitable Marxist philosopher Slavoj Žižek weighed in during an interview with Quartz. When asked if it’s okay to punch Nazis, he gave a confident answer:

“No! If there is violence needed, I’m more for Gandhian, passive violence,” Žižek answered.