Who knows how many journalists have personal political sympathies to the left or right. What is certain is that it should not matter, writes Jonathan Green.

Here's a thing about journalism: it's a craft, a set of trade skills that can be applied pretty universally to a range of situations.

And that's what makes the job such an endless fascination, the daily compilation of instant understanding, the constant search to arrange the varied aspects of an argument and present them, not according to your own judgment of right or wrong, but for the consideration of others.

That is the service. The true calling at the heart of the craft: to simply inform without bias or favour.

Which is why journalism has historically built trust among its consumers ... if journalism were a polemic, if it became a cynical exercise in the promotion of any or various propositions, then it would cease to fill any laudable social function. At best it would be entertainment. At worst, propaganda. In either case, it would hardly merit the range of privileges we accord the worthier work of the fourth estate.

As has been extensively documented, this edifice, a cornerstone of smart democratic practice, is crumbling. The happy commercial accidents that funded journalism businesses for a century and a half and led to a political culture of well-scrutinised accountability are going, going, almost gone. We are yet to stumble upon new ones.

Two kinds of journalism look certain to endure. The subspecies that has perhaps the best chance of commercial survival is the debased populism of the tabloids, the papers that drip faux familiarity - they're "For Your City" - then feed their readers on a patronising diet of calculated political fabrication, fear mongering and pap.

The readership is huge, but it's an abusive relationship based on the daily betrayal of trust.

The other 'journalism' that 'works' in this uncertain environment is the sort of polemic that may have limited commercial worth but enormous political purpose ... and this might be the most unfortunate mutation of the craft in our times, turning journalism to cynically political purpose while claiming all the protections, rights and respectability of the fourth estate.

Fox News - that's the best example of how this works: an entirely parallel universe that determines its own agenda, facts and logic according to an often bellicose political mission. This is not journalism created with intellectual curiosity to inform; this is journalism dedicated to the insistent prosecution of a series of political propositions.

We see its muted fellow travellers in our own TV and press, most notably in our national broadsheet The Australian, a paper whose political purpose and occasional flights of "truthiness" can routinely obscure its better journalistic angels.

And then we have the opinion formers of the tabloid blogosphere. Little s-bends of ill-humour like the Daily Telegraph's Tim Blair, or great vaulted Taj Mahals of polished ego like the Herald Sun's Andrew Bolt. They are not for profit. They are for politics and influence, pivots of opinion, so loud, so insistent, so ubiquitous that they are capable of turning the national mind.

And they deny the fundamental spirit of this vanishing craft of journalism, while arguing furiously for their own well-established right to speak, and against the apparently creeping menace of leftist collusion that dominates most other media - particularly the ABC - that labours under the great misfortune of not being them.

Lately from this politicised fringe we have had a repeated argument: that journalism here at the ABC is some act of leftist collectivism, a case made conclusive by the absence of figures that might be clearly identified, by the likes of Bolt or Gerard Henderson, as being "of the right".

Which misses the point entirely. Journalism is neither of the right or left; it is, for want of something less pompous, of the truth. In any journalism worth its salt the convictions of the reporter are an irrelevance and the journalism that might be produced under the influence of personal prejudice is a betrayal of professional practice and the implied trust of all who consume it.

But it would seem, on the evidence of their own work, that this is not how these figures of the right see the role of journalism.

The likes of Bolt struggle with the notion that journalism might be practiced with calm objectivity and simple curiosity ... because in the paranoid, fact defying columns of the proselytising right, where climate change is a religious figment, Stephen Conroy is Stalin and any measured objective assessment of reality is dismissed as being 'of the left', the facts are mutable servants of argument.

Who knows how many journalists have personal political sympathies to the left or right. What is certain is that it should not matter.

Journalism is a trade in which personal conviction is one of two things: an irrelevance or a death sentence.

Journalism tainted by conviction just isn't. That's the simple truth of it.

Jonathan Green is presenter of Sunday Extra on Radio National and the former editor of The Drum. Read his full profile here.