There are three plain ways you can tell a Liberal voter from an ordinary, decent human being.

One is they deny their emotions. Another is they suppress a lot of relevant information. The third is they refuse to admit they’re a Liberal voter. “My vote is between me and my conscience,” they say. Or “I’m a swinging voter”. Or “I used to vote Labor but I’m considering my options”. Ask them which Labor candidate they voted for and they have no idea.

Overt Liberal voters are few and far between now. Try selling “Liberal and proud of it” T-shirts on the Mosman ferry for a dollar each and see how you do.

They deny their emotions always. “Not angry, disappointed,” they say upon being sacked and humiliated, “disappointed at not being able to continue to serve the Australian people as I have in the past. I was hoping to do so in the future but it seems it is not to be.”

(This is translation means, “I want to rip his throat out. I’m looking up scandal on him and intriguing to overthrow him. Sack me, will he? He’d better watch his back.”)

They suppress information in subtler ways. Dissident opinion is quietly removed from the Op Ed pages, and Miranda Devine retained. Letters critical of Gerard Henderson never published. Inquiries into Alan Jones’s departure from Kings discouraged. Suburban newspapers are bought up by Murdoch, and radio stations by Singo, which toe the Liberal Party line thereafter.

The Liberals know now, you see, that they can’t win any public argument, the facts are always against them, so what they do — if they can — is turn off the dissidents’ microphones. They downplay, as news, the AWB scandal, in which, if you recall, Alexander Downer didn’t remember the 298 million dollars that went to Saddam Hussein. They ask no apology from John Howard — even now — for calling Barack Obama a friend of terrorists.

They suppress close-up photos of boat people, knowing this would humanise them, and show instead far-off images of them looking like crawling insects waving their feelers. They call David Hicks a “confessed terrorism supporter” instead of “torture victim”. They make no criticism of the interrogators who told Mamdouh Habib his wife and children were dead.

They avoid all public debate (Gerard Henderson has repeatedly refused me one for 20 years; I am too barbarous to share a stage with, apparently), preferring to snipe from the sidelines, often with considerable skill. And they rarely discuss the issues, preferring to blacken or trivialise their opponent’s character. “Bleeding heart.” “Old-style, clapped-out 60s leftie.” “Chardonnay socialist.” “The Commentariat.” “The latte-sipping elites.” If they can’t find a flaw in your argument, Mark Twain said, they will soon find a flaw in your character.

They simplify their opponents into handy, belittling cartoons. Kim Beazley the timid, lazy glutton. Paul Keating the vulgar foul-mouthed groper of royalty. Bob Brown the kooky impractical foggy idealist, though he’s never been wrong about anything thus far. Bob Ellis the untidy, shambling eccentric, my 20 years on arts committees and my 30 years as a prize-winning moral essayist and playwright omitted. Germaine Greer the crazed bag lady, though she’s the most impressive public intellectual since George Bernard Shaw. And so on.

They squeeze you down to a grumpy prattling muppet and kick you aside contemptuously. They do it because they can. They command the column space, and the airtime, and they can.

I’ve noticed lately another trick they have, which is when on panels to state the obvious at stupefying length. Peter Hartcher, lately on stage with me, revealed with evident astonishment that in a faraway country called — let me see — what was it? oh yes — Australia, an election of both Houses of Parliament took place in — let me see, what was it? — 2007, in which the two main political opponents John Howard and … Kevin Rudd were vying for the Prime Ministership of that country; and it seemed for a good while that Kevin Rudd had at least the initial advantage, being younger than Howard, and Howard, paradoxically, being older than Rudd … And all the while I was busting to talk, and I couldn’t, because he was stating the obvious and eating up time that could have been thoughtfully or contentiously employed by a non-Liberal voter on ABC television.

Howard did this all the time, and Ruddock made an art form of it. “We must deny the terrorists,” Margaret Thatcher famously said, “the oxygen of publicity.” And the Liberals have learned well the many ways to do it. Piers Akerman, for instance, on The Insiders.

The suppression of relevant information. It’s what the Liberals do.

I think we should begin “outing” Liberals, and by this new McCarthyism shame them out of public life.

We could call it the Register of Liberals, and post it on an ever-expanding website.

It can’t be libellous, can it?

Makes you wonder.