Leftists embarked on a crusade to exterminate hate speech. Initially, the idea was reasonable: to stop the hostile propaganda, that of Neo-Nazis and Islamic radicals. In the spirit of political correctness and equality, the premise was generalized and all hate speech outlawed. Fighting the enemies (Nazis and Islamists) gave way to fighting extreme ideas in general, and even stylistics.
Extreme views are indispensable to societies. Atheism, secularism, democracy, and workers’ welfare were originally extreme ideas.
Nor could the violence be opposed per se. Nazism was overturned by violence, and Soviet communism – by threat of violence. The American North used violence against the South. Violence overturned monarchies and totalitarian regimes. Violence established all modern states and shaped their borders. Threat of police violence keeps criminals at bay.

Rejection of extremism and violence preserves status quo, but circumstances change, and status quo becomes untenable. Absent of long-term discussion of other – including extreme – views, accidental views will come to power. They will fail, and people will try other views. Societies that suppress discussion and evolution of ideas fail in convulsions.

Threat of violence forces adjustment and accommodation. When public discussion of violent means is prohibited, people imagine safety and do not adjust to their enemies. Discontent balloons. Slow perpetual readjustment among various groups gives way to accumulation of hatred which eventually erupts in major bloodshed.

It is not incidental that communist countries suppressed free speech. The left push a very wrong policy of social engineering. They set shining goals, presume the subject societies mathematically rational and susceptible to planning, and mandate the policies to reach the desired goals. Free speech harms the left on three counts: it introduces new ideas which weren’t included in the original calculations, questions the goals and policies, and proves the rationalist policies wrong. In the ostensibly free countries, the left cannot suppress all free speech, but jump on the opportunity to suppress the views most hostile to their policies. The views most critical of the current policies are, by definition, extremist. Switching to a different policy is not simple, and requires much changes, clashes, and perhaps violence. Principled opponents of the left thus necessarily call to extremism and violence. The only alternative is social engineering.