Milo Yiannopoulos may now be heading for Australia — with his visa issues apparently resolved — and the free speech debate that followed him on his tour of colleges in the US is just as immediate on this side of the Pacific.

Right-wing commentators such as Yiannopoulos, Richard Spencer and Ben Shapiro have been making waves visiting university campuses across America, resulting in protest that's occasionally violent, as well as calls for bans and boycotts.

Closer to home, the University of Western Australia cancelled a talk by an American paediatrician in August last year following criticism of his views on transgender people.

And in September, commentator Bettina Arndt attracted lively protest around the country on a campus speaking tour where she spoke of a "manufactured rape crisis" at tertiary institutions.

There's no doubt the question of exactly who gets to say what on campus is a live issue.

Even the Federal Government seems to have its concerns. Last November Education Minister Dan Tehan announced an independent review into what some describe as a "free speech crisis" in Australian universities.

But is freedom of expression really being muzzled? It's a question not just for the activists picketing campus venues — but also for philosophers.

An offence against knowledge

Perhaps the most famous philosophical defence of freedom of speech is that articulated by John Stuart Mill in his 1859 work On Liberty. Mill argues that the silencing of any opinion at all, no matter how wrong or obnoxious, is itself an offence against knowledge.

Human understanding, he believes, is best promoted by a no-holds-barred wrangle between orthodoxy and heterodoxy, between truth and falsehood — and it's essential that this wrangle should take place in the public square.

Mill's formula for free speech dovetails nicely with the concept of the "marketplace of ideas", an imagined realm where consumers of knowledge pick only the most reputable and reliable brands, and thus over time the stock of truth inevitably outperforms that of error.

John Stuart Mill, author of On Liberty. ( Wikipedia: London Stereoscopic Company )

This is free speech fundamentalism, tailored to the rough-and-tumble of communication in open democracies, and ideally espoused by anyone of any political persuasion who values genuine wisdom.

Who could deny, then, that the university — itself a microcosm of democratic society, and increasingly understood as a vibrant part of the market economy — should be a forum where any and every opinion can be heard, tried and tested?

Insight or anything goes?

Robert Simpson, an Australian philosopher working at University College London, specialises in this sort of debate around free speech and liberalism.

He's sceptical of the idea that the university campus should be an anything-goes environment.

"This idea that university is supposed to be a microcosm of democratic society at large is contestable," he says.

"In the great wave of social democratic reforms that swept through Western liberal countries after World War II, there was a massive expansion of the university sector, a huge amount of public money being poured into tertiary education."

What was the idea behind this? Dr Simpson says Western nations were trying to improve the epistemic quality of society — in essence, to have a more informed public.

"The thought that merely being engaged in a heated altercation attains to some democratic ideal is implausible to me," he says.

"Mere dissent, mere altercation doesn't have a great deal of democratic value.

"What we want from democracy is an exchange of ideas between different people where there's some movement toward a shared understanding, so that we can jointly govern ourselves."

Dr Simpson believes it would be detrimental to universities if the culture of social media came to define debate on campus.

Like Yiannopoulos, Richard Spencer attracts vocal protests when he speaks on campus. ( Getty Images: Evelyn Hockstein/The Washington Post )

What about professional trolls?

But if universities are supposed to foster some sort of democratic competence, rather than just mirroring the chaos of public communication, what about the often-encountered argument that students are too shut off from "real life"? That they're too protected from anything or anyone that might offend?

Racists, misogynists and other questionable individuals are out there in the world. Surely the opportunity to hear and debate these people constitutes a valuable form of learning?

Not so, according to Dr Simpson.

"John Stuart Mill said that we need to hear the very best arguments on behalf of views that we reject," he points out.

"I'm not going to learn a lot from having an encounter with a professional troll.

"The argument has to be with someone who sees my anti-racist position and disagrees with it, but disagrees with it in something other than just an angry, trying-to-start-a-race-riot kind of way."

Given that Yiannopoulos describes himself as a "troll" who "gets off … when people are yelling in the streets", it seems difficult to argue that his contribution to campus debate is a positive one.

But not all speakers who are "no-platformed" are trolls.

Protests followed Ben Shapiro on his tour to the University of Utah campus in Salt Lake City. ( Getty Images: George Frey )

"There is something to this idea that in order to be fully justified in holding our views, we need to know what we'd say to the most intelligent and capable defenders of opposing views," Dr Simpson says.

"But that's an argument for staging an encounter with those most intelligent and capable defenders — not just staging an encounter with any old person who's willing to go up on stage and say provocative things."

Where are the left-wing Milo Yiannopouloses?

Debate on campus, then, should be regulated according to a sort of intellectual quality control, in much the same way as academic teaching and research is regulated (and sometimes suppressed) by standards of professional competence.

But this doesn't account for the politics of the situation — the fact that whenever an individual is disinvited or no-platformed from speaking on campus, he or she almost always leans toward the conservative end of the spectrum.

"The thing that concerns me is that we don't want students of any political ilk to think they know all the answers," Dr Simpson says.

"It's hard for them to have the kind of porousness needed for learning if they rock up to university thinking that they've got nothing to learn.

"If they think they're the ones who should be imposing conclusions on other people, then something's gone wrong, whatever political commitments they might have."

In Dr Simpson's assessment, the student body is progressive because they're young and middle class, and young middle-class people are overwhelmingly progressive.

But he points out that other parts of universities lean the opposite way.

"Economics departments are overwhelmingly aligned with neo-conservative or libertarian political movements," he says.

"So if you're a Marxist economist, it's really hard to get a job at a university nowadays."

But what if you're a Marxist who just wants to stir up trouble by giving a provocative talk on campus? Where is the left-wing Milo Yiannopoulos, and why isn't he being no-platformed up and down the country?

"That's a very good question," Dr Simpson says.

"It's striking that provocative hard-line leftists don't seem to get the audience in the first place.

"This could be because the things they're saying are just a more aggressive or militant version of what university faculty think, so it's not that interesting for students to hear that person come and speak.

"I think there are a few people in philosophy circles who'd be delighted to become the left-wing Milo Yiannopoulos, but it's not so easy for them to get out there and say the things that get up people's noses on campus."

A review of free speech might not be such a bad idea

At a time when the Federal Government has ordered a review into freedom of expression at Australia's universities, Dr Simpson is sceptical about the notion of a "free speech crisis" on campus. But that doesn't mean he thinks the review is completely misguided.

"Framing it in the language of a 'free speech crisis' suggests that we already know what's going on, and we're just trying to find out how bad it is," he says.

"Sometimes a certain kind of progressive will be very quick to say, 'it's all just a beat-up, there's nothing going on', and that response worries me.

"I think there is something going on, that the culture of universities is in a state of flux, and that's affecting people's ability to speak on campus in a way that we at least need to understand.

"But the term 'free speech crisis' presupposes that we want universities to be places where open-ended free communication is nurtured and facilitated — and that subtly but importantly misconstrues the kind of discursive community that a university is supposed to be."