You’d have to be a brave soul to join some of the debating societies at Goldsmiths’s. A college that was once the quirky haunt of irreverent new ideas makes headlines for the kind of advanced “safe space” clashes which use the language of intimidation to silence the people who campaigners don’t approve of. This month, human rights activist and feminist Maryam Namazie was denounced for “Islamophobia” and treated to a group of male students chanting about feeling “intimidated”, before one tried to silence her by pulling out her projector plug.

Other colleges have been caught up in rows about which speakers may share their thoughts with students who might find them disagreeable and thus “unsafe”. It remains hard, however, to beat Manchester University’s student union, which managed to ban Julie Bindel, an outspoken feminist, from a session entitled,” Does modern feminism have a problem with free speech?” on the grounds of alleged “transphobia”, before she got there. Little by little, identity politics devours itself, leaving only the thin gruel of received doctrine and a set menu of thoughts.

I have been thinking about this with the long lens of Britain’s history of defending liberal freedoms, making a series on Radio 4 called Liberalism, the Grand Tour. It starts with John Locke, the late 17th-century philosopher whose writings in favour of constraining the arbitrary power of the King were burned outside the Bodleian in 1683 as “damnable doctrines destructive to the sacred persons of princes”. The freedom to challenge sacred doctrines, whether held by persons, princes, popes or self-righteous campaigners, is a fundamental one and it needs defending.

Of course, sensible people don’t want to offend others by using the wrong language and it is social progress that lets us shave the negative edge off language about sexual and ethnic minorities. Unchecked, it gallops into an esoteric thought-world. (A dissection of the approved language of transgenderism on the BBC website says a non-transgender person should be described as “cisgender”. This would bamboozle around 99 per cent of the audience).

The more ideologically narrow-minded or manipulative will demand the restriction of free speech because in one form or another they always have. So the Islamic Society protesters at Goldsmiths couched their objections in terms of feeling “extremely uncomfortable” about Namazie’s hostility to some aspects of political Islam. Who is to tell the gentleman that “feeling uncomfortable” about an opposing view is part and parcel of debate?

Locke, I’m glad to report, did not give up easily and neither should we. Fleeing Oxford, he sought out Dutch free- thinkers, challenging the Church and writing his Letter Concerning Toleration. If his concerns were those of the day, his message should ring out now. How we express ourselves and what we argue for can only be interfered with to prevent harm — not because it makes someone else feel annoyed.

Locke knew what it was to live in a time when “safe spaces” were the difference between life and death for dissenters. The phrase has become a sham, and a thoroughly intolerant one. It’s high time Locke’s academic descendants were more forceful in saying so.

Liberalism, the Grand Tour, is on Radio 4 every day at 1.45pm, with an omnibus edition this Friday at 9pm.