While the government’s proposals to amend section 18C of the Racial Discrimination Act have prompted considerable debate, it hasn’t been particularly useful debate — plenty of heat and not much light, as Tim Soutphommasane described it, and people taking more or less standard positions — the Left strongly opposed, middle-aged white men (like me) supportive.

One interesting feature is that Holocaust denialism has emerged as a totemic example of what is supposedly beyond the pale in public debate. Labor repeatedly challenged the government to explain whether Holocaust denialism would be allowed under the new laws, if enacted; this week, Fairfax asked us to be alarmed that the changes proposed by Attorney-General George Brandis would allow Holocaust denialism, according to advice to the New South Wales government.

Holocaust denialism is the vile ranting of anti-Semites, and no doubt profoundly wounding both to Holocaust survivors and their families. But Australia doesn’t have a problem of Holocaust denialism: whenever the issue has been raised, the same example is always cited. Europe has a problem with Holocaust denialism, yes — and it’s outlawed in Germany — but Australia doesn’t. We may have a problem with anti-Semitism, but it doesn’t take the form of Holocaust denialism.

Moreover, it is seem to be the kind of case that the government’s changes to 18C seem designed to address. It is offensive and deeply wounding, but it does not cause or urge direct and demonstrable harm in the way an anti-Semite urging violence against Jews would — the sort of speech that, by and large, everyone is in agreement should be prohibited. That may not be the case in Germany, where there are demonstrated links between Holocaust denialism and neo-Nazism, which may well lead to violence against Jews, but even in that instance we’re talking about an indirect harm.

As Soutphommasane has correctly explained, there’s rampant inconsistency in all this. The Abbott government isn’t racing to remove prohibitions on all language short of urgings to violence in Parliament, for example. It isn’t even racing to remove much more significant impediments to free speech, like defamation law.

But what sort of speech should be banned, if we agree that all speech short of that which leads to, or is intended to cause, actual harm, is permitted?

Let’s do a quick check of recent history. There was the Keating government’s assault on free speech, when it outlawed Albert Langer’s urging of voters to vote in a way that was formal but didn’t allocate preferences. Langer was later injuncted from campaigning about it, and was actually jailed for contempt of court. The prohibition was later removed and the loophole that Langer exploited was fixed, but not before Langer had spent three weeks in jail purely for advocating a particular method of voting.

And it was on the watch of then-attorney general Philip Ruddock that online discussion of euthanasia — or “counseling suicide” as it was described in legislation — was banned in 2005, primarily to stop the activities of Dr Philip Nitschke, who continues to be harried by authorities to this day because of it. Discussing euthanasia is plainly not the urging of harm on others, but informing people of options if they themselves wish to end their lives.

Ruddock also refused to remove the old crime of sedition from his overhauled anti-terror laws, despite a review he himself commissioned recommending he do so; indeed, Ruddock significantly expanded the offence of urging the overthrow of the government or urging violence within the community, removing conditions relating to intention and actual violence resulting from a statement. Labor dumped the offence entirely when Kevin Rudd became prime minister, and the Abbott government — so far — has not indicated a wish to restore sedition, however much it appears to want to return to the 18th century.

“… there’s a particular form of speech in Australia that does, demonstrably, cause harm: anti-vaccination propaganda.”

That brings us to the example of Islamic extremist Belal Khazaal, jailed for 12 years in 2012 for cutting and pasting together a sloppy e-book of material supporting jihad. Khazaal was jailed because of one of the Howard government’s draconian anti-terror laws, s.101.5 of the Criminal Code, which makes it an offence to collect or make a document that “is connected with preparation for, the engagement of a person in, or assistance in a terrorist act” — even if it’s not intentional.

To his considerable credit, Chris Berg is probably the only non-lawyer to sound the alarm about what happened to Khazaal. “Words are cheap,” Berg wrote in 2012. “The Anarchist Cookbook provides more technical detail than Khazaal offered, and is free to read across the internet. Belal Khazaal may be a bad guy. He may deserve to be in prison … But if he deserves to be in prison in Australia, he deserves to be there for a greater crime than making an e-book.”

Khazaal’s case admittedly gets us close to the boundary of speech that urges people to harm others, even if “cake throwing” and “hitting with a hammer” sounds more like a Warner Bros cartoon than jihad. It’s the lack of specificity that’s the problem with Khazaal’s literary effort, since he urged violence against, well, most of the Western world. And, as Berg notes, it’s hard to say what particular harm has come from Khazaal’s work, especially given the source material is still available online. If you’re an incipient jihadist, it’s unlikely Provision in the Rules of Jihad is the dangerous material radicalising you.

But there’s a particular form of speech in Australia that does, demonstrably, cause harm: anti-vaccination propaganda. Unlike other forms of denialism, vaccination denialism kills. It has a provable body count, in terms of the number of children who die from preventable diseases either because their own parents have refused to vaccinate them, or because, despite their own parents doing the right thing and vaccinating them, they were exposed to an unvaccinated child while only partially protected, or because they were babies too young for their shots and they have been exposed to unvaccinated children.

To the extent that the lies of anti-vaccination campaigners influence a small number of parents to not vaccinate their children, it leads to the deaths of children from preventable diseases and leads to the illnesses and hospitalisation of others. It is speech that causes harm — and death.

On that basis, should anti-vaccination speech be banned? It’s a hard case: one is loath to add to the conspiracy theories and sense of persecution of people who are either sublimely stupid or who in their inner-suburban affluence believe they’re too good for vaccination, and don’t want to be part of any herd whose immunity is critical. Moreover, in many cases anti-vaxxers genuinely believe the lies they spout about Big Pharma conspiracies, autism and chemicals. None of them mean to cause harm; they just wilfully refuse to see the harm they cause.

A better response might be to stop facilitating denialism first before starting to ban it. The denialist “Australian Vaccination Network” was forced to change its name and recently (finally) lost its charity status. Queensland Health Minister Lawrence Springborg has commendably raised the issue of making it significantly harder for parents to claim “conscientious objection” status. We should go further and ensure parents who, without medical approval (some kids can’t be vaccinated safely), refuse vaccination do not receive family tax benefits, as proposed by Kevin Rudd before last year’s election. The media — especially television networks — could stop pretending there’s a “debate” about vaccination. That might help stop the death toll inflicted by the anti-vaccination lobby better than banning what they say.

But it’s odd that we’re talking about other examples of harmful speech when there’s a much more pressing one right under our noses.