The most powerful leader in the world tweets like a teenage Nazi on 4chan whose sole aim is to create outrage. Three retweets of anti-Muslim hatred first tweeted by the deputy leader of a British neo-Nazi group cause global outrage. British politics becomes consumed by the issue. Parliament even holds a special session to allow MPs to denounce the tweeter. And a tiny British far-right organisation, barely known even to most British people, but whose whole existence is rooted in generating outrage, achieves what it wants and on a global scale. “Donald Trump himself has retweeted these videos … God bless you Trump!” it gleefully tweets.

Welcome to politics 2017-style.

It is astonishing that the president of the United States should retweet obnoxious videos, the principal aim of which was to whip up hostility towards Muslims; equally so that he should blithely ignore not just their provenance but also that at least one was not what it purported to be.

But if the video was fake, there was also something concocted about the controversy. One side wanted to provoke outrage. The other side duly obliged and expressed outrage. And on both sides, the signalling – “Look at me, I’m saying the right things” – seemed to matter more than the content. From Trump’s original tweets to newspaper headlines that Trump was “not wanted” in Britain, much of the controversy had the feel less of a political debate than of online trolling.

In her new book Kill All Normies, the writer Angela Nagle tracks the rise of the online “alt-right”. A new culture has developed, she argues, on internet forums such as 4chan and Reddit, which sees the transgression of mainstream liberal norms as a good in itself, irrespective of the content and consequences of such transgression. This helped forge a new anti-establishment politics, a kind of counter-culture rooted in the embrace of reactionary, bigoted, racist and misogynistic attitudes in which the ability to create outrage became the principal currency.

This reactionary counter-culture has spilled into the offline world and right into the White House. Donald Trump appropriated the essence, if not the tone, of the online alt-right transgressors, perfecting a mixture of narcissism, self-aggrandisement and the elicitation of liberal outrage that helped intoxicate many disaffected voters. It turned rage about the political elite into hostility against the supposed symbols of elite politics – Muslims, migrants, the marginalised. Trumpism is the product of the evacuation of politics from the political sphere, the replacement of policies and ideas with symbols and signalling. Trump’s policies are, of course, deeply political and have grave real-life consequences for everyone from Muslims to poor Americans on Obamacare, from African Americans to hurricane victims in Puerto Rico.

Yet, from the Mexican wall to the visa restrictions on Muslim majority countries, the public pronouncements are less about practical policies than about expressing the right attitude and of being contemptuous of liberal norms. Symbolism has always been part of politics. In the age of Trump, it is politics. The fact that a single series of tweets should so dominate British politics suggests that, just as Trump and his supporters define themselves through eliciting outrage, so many of his critics do so by expressing it. In a special parliamentary session, MPs lined up to pour opprobrium over the US president. The press was equally self-righteous; Trump should be banned from visiting “Britain’s multicultural nation until he learns some manners”, as the Independent put it. This was as much signalling as were Trump’s tweets.

Facebook Twitter Pinterest Anjem Choudary: ‘an obnoxious clown with good television skills’. Photograph: Tim Ireland/AP

The one clear winner is Britain First. The thrusting of an odious fringe group into the global spotlight has led to a debate about how such a story should be reported. The media, many protest, should not be giving a hate group so much publicity. It is true that the media often make insignificant figures appear important because they fit a particular narrative. For years, Anjem Choudary, founder of the Islamist group al-Muhajiroun, which only ever possessed a handful of members, was forever to be found on our TV screens, as if he was an important voice within the “Muslim community”, rather than an obnoxious clown with good televisual skills.

In the case of Britain First, however, it was the president who put it in the public eye. The question the media need to ask themselves is not if they should give publicity to a fringe group, but why they became obsessed with Trump’s tweets. At the same time, it is important that the media do not censor debates or refuse to cover hate groups simply because their views are unsavoury. In Kill All Normies, Nagle argues that restrictions of “political correctness” and of liberal “call-out culture” helped create a backlash that turned into the transgressive alt-right. Some make a similar argument about Britain First. “Britain first [sic] is what you get when you reject legitimate concerns about Islam and uncontrolled immigration,” tweeted former Ukip and Leave EU funder Arron Banks.

It is true that in recent years there has developed a culture of censorship in discussion of Islam; from art to social policy, the fear of giving offence, or of appearing racist, has often curtailed debate. I have long pushed back against this censorious culture. Last month, I wrote a chapter in the new Runnymede Trust report on Islamophobia, questioning the very use of the term because it conflates bigotry against Muslims with criticisms of Islam. Too often, I argued in the report, criticism of Islam is deemed illegitimate because it is judged to be “Islamophobic”. Nothing should be unsayable simply because someone finds it offensive or because it is culturally or religiously sensitive.

At the same time, I observed, those who promote hatred against Muslims often dismiss condemnation of that hatred as stemming from an illegitimate desire to avoid criticism of Islam. For this is the other side of contemporary culture: a hostility to Muslims that leads many to rail against Muslim immigration and to regard Islam as an existential threat to the west. Not just the far-right but many liberals, too, have helped stoke such fears.

Britain First is not the creation of constraints on speech. It is a product of a bigoted view of Muslims. It is a violent group that considers all Muslim elected officials as “occupiers” and promised “direct action” against London’s mayor, Sadiq Khan, and Tory cabinet minister Sajid Javid. These are the views and actions of racists, not of those frustrated with restrictions on free speech.

It is morally incumbent on those who argue for free speech and for an open debate on sensitive issues to challenge such bigotry wherever it may manifest itself. In today’s polarised culture, in which signalling one’s virtue or vice is regarded as more important than thinking deeply about an issue, the willingness both to defend free speech and challenge bigotry is too often in short supply.