If the great campaigners for free speech of the past, such as Baruch Spinoza or Mary Wollstonecraft or Frederick Douglass, were alive today, “they would surely declare the 21st century an unprecedented golden age”. So suggests Jacob Mchangama in his new history of free speech. It’s a claim that might raise a few eyebrows. This, after all, is an age in which, from China to Saudi Arabia, dictatorial rulers imprison and kill political opponents with impunity. An age in which governments in formally democratic nations such as India use the judicial system to try to silence critics. An age in which more than 1,400 journalists have been murdered in 30 years. An age in which governments across the globe desperately seek ways of curbing speech on social media they consider dangerous. And in which, in the west, there is a constant debate about “cancel culture” and the erosion of academic freedom. Mchangama, a leading campaigner for free speech, is not trying to dismiss the reality of contemporary censorship. He is suggesting, rather, that in historical terms, we have never been more free to speak our minds. But this leads to a paradox. The very fact that, certainly in the west, we live in far more open societies has led many to be sanguine and dismissive of the threat that restrictions on speech can impose upon us. The very success of historical struggles can obscure the lessons of those struggles. Historically, the demand for free speech was at the heart of the fight for social justice. From the challenge posed by freethinkers in 10th-century Islam to the abolitionist struggle in 19th-century America, from the suffragette movement to campaigns for liberation from colonial rule, there has long been a recognition that democracy, social justice and free speech go hand in hand and that censorship was a weapon wielded by the powerful to stymie social change. Today, though, the issues seem more confusing. Much censorship, particularly in liberal democracies, is imposed in the name of protecting not the powerful but the powerless or the vulnerable: laws against hate speech, for instance, or restricting the scope of racists or bigots. And where once the left was clearly opposed to censorship, many now support restrictions in the name of the progressive good. As the left has vacated the ground of free speech, the right and the far right have become encamped upon it. This has further distorted the debate, the cause of free speech coming to be seen as the property of the right, making many on the left even more wary of the idea. One of the ironies, though, is that many arguments used today to defend speech restrictions as protections for the powerless are often the same as those once used by the powerful to protect their interests from challenge. When the US abolitionist newspaper editor Elijah Lovejoy was murdered in 1837 by a pro-slavery mob in Illinois, a southern newspaper blamed him for his own death, as he had “utterly disregarded the sentiments of a large majority of the people of that place”. A century and a half later, we heard the same arguments in calls for the banning of The Satanic Verses or in claims that the Charlie Hebdo cartoonists were responsible for their own deaths, because they, too, had “disregarded the sentiments” of many Muslims. Or take hate speech. In the 1950s, there was a major debate about the wording of the International Covenant on Civil and Political Rights, one of the seminal documents of human rights, adopted by the UN in 1966. The draft proposal sought to prohibit “any advocacy of national, racial or religious hostility that constitutes an incitement to violence”. The Soviet Union wanted to delete the reference to violence and make any form of hatred illegal. Such a move, warned Eleanor Roosevelt, chair of the drafting committee, “would be extremely dangerous” as “any criticism of public or religious authorities might all too easily be described as incitement to hatred and consequently prohibited”. Half a century on, Roosevelt’s warning seems highly prescient. Instances in which the expansion of speech has facilitated the spread of obnoxious or dangerous ideas are well-documented: from the newly invented printing press giving fuel to witch-hunts in early modern Europe; to newspapers playing a major role in whipping up the racist frenzy that led to lynchings in 19th-century America; to the media’s role in the 20th century in fomenting hatred against Jews in Germany and Tutsis in Rwanda. Yet we can also see from the historical record that while it is necessary to legally curtail incitement to violence, trying to combat hatred more broadly through censorship can be both ineffective and dangerous. One of the deepest-held beliefs about the dangers of free speech is the Weimar myth: the belief that unrestrained freedom of speech allowed the Nazis to spread their poisonous ideas in 1920s Germany and that restrictions on speech and the suppression of antisemitic propaganda would have stalled the rise of Hitler. In fact, the Weimar republic, while constitutionally supportive of free speech, possessed what we would now call hate speech laws and powers to shut down newspapers. Hundreds of Nazis were prosecuted under these laws. Between 1923 and 1933, the viciously antisemitic newspaper Der Stürmer was either confiscated or tried in court on 36 occasions and its editor, Julius Streicher, twice jailed. Many scholars argue that despite such laws Weimar courts were unduly lenient towards hate-mongers and that judges sympathised with Nazi aims. Other studies suggest that such leniency was the exception, not the rule. Wherever the truth lies in this debate, the primary failure in preventing the rise of Nazism was not legal but political. And this is true of hatred and bigotry today. We often forget, too, that the victims of censorship are more often than not minorities and those fighting for social change. From Indian climate change activists being charged with “promoting enmity between communities” to British police charging feminists with “hate crimes”, censorship in the name of “preventing hatred” is widely used to target social activists. We are the inheritors of centuries of struggle against restrictions on what we are able to say. If we forget the lessons of those struggles, we are in danger also of letting the gains of those struggles slip away. Kenan Malik is an Observer columist