Can somebody tell me what happened? Can someone explain how in the space of just a decade our public discussion has been hijacked by the ignorant and the bigoted and their boosters in the mass media?

And there's a more important question, how did the once authoritative political class let it happen?

You may or may not have watched Four Corners on Monday: a gripping report that recalled the High Court's Mabo finding in 1992 and Paul Keating's subsequent political quest to put legislation round the court's repudiation of terra nullius and enshrining of native title. The history of our Commonwealth has had few more significant - or challenging - turning points.

Like all documentaries of this type, the Four Corners report did more than simply shed light on its central subject. There was much else to see besides, little snippets that also illuminated the political and media culture of the time. This exchange between Paul Keating and a talkback caller on John Laws' 2UE morning program in 1993 was stunning, an absolute show stopper.

Caller: Good morning. John Laws: Okay, the Prime Minister is here. Caller: Yes, good morning. Just a very broad question, Mr Keating, is: why does your government see the Aboriginal people as a much more equal people than the average white Australian? Paul Keating: We don't. We see them as equal. Caller: Well, you might say that, but all the indications are that you don't. Paul Keating: But what's implied in your question is that you don't; you think that non-Aboriginal Australians, there ought to be discrimination in their favour against blacks. Caller: Not... whatsoever. I... I don't say that at all. But my... myself and every person I talk to - and I'm not racist - but every person I talk to... Paul Keating: But that's what they all say, don't they? They put these questions - they always say, "I'm not racist, but, you know, I don't believe that Aboriginal Australians ought to have a basis in equality with non-Aboriginal Australians. Well, of course, that's part of the problem. Caller: Aren't they more equal than us at the moment, with the preferences they get? Paul Keating: More equal? They were... I mean, it's not for me to be giving you a history lesson - they were largely dispossessed of the land they held. Caller: There's a question over that. I think a lot of people will tell you that. You're telling us one thing... Paul Keating: Well, if you're sitting on the title of any block of land in NSW, you can bet an Aboriginal person at some stage was dispossessed of it. Caller: You know that for sure, do you? Paul Keating: Of course we know it for sure! Caller: Yeah, [inaudible]. Paul Keating: You're challenging the High Court decision, are you? You're saying the High Court got this all wrong. Caller: No, I'm not saying that at all! I wouldn't know who was on the High Court. Paul Keating: Well, why don't you sign off, if you don't know anything about it and you're not interested. Good bye! Caller: Yeah, well, that's your ... Paul Keating: No, I mean, you can't challenge these things and then say, "I don't know about them". John Laws: Oh well, he's gone.

It really sets you back in your chair. From a contemporary perspective this seems an extraordinary act of political courage, of reckless honesty. A politician on talkback radio telling someone with no real knowledge of the issue beyond a gut feel that it rankles their deepest prejudices, that they are not entitled, under those terms, to enter the discussion.

You just know that today, the caller would be indulged; their opinion flattered with undue attention. So it is that today we see a political discussion that rather than excluding or marginalising the voices of the uninformed, angry and blindly polemical, is in fact conditioned, directed and dominated by them.

Look at our endless to and fro over asylum seekers... a debate in which the national government happily sets aside its obligations under international law and convention, never mind any reasonable notion of what is moral, in order to placate a vocal core of constituents whose shallow xenophobia and nebulous economic anxieties are amplified by talk back radio and the tabloids of TV and print.

Same for climate change. Five years ago we had something near to a national consensus based on unambiguous science, a consensus cynically talked down often through shorthand distortions and misrepresentations pitched at the uninformed.

Today few politicians dare confront these tides or take a stand against it. The tail has wagged the dog.

Where Paul Keating thought nothing of speaking his mind, Julia Gillard sits in the same studio as Alan Jones, is called a liar to her face and brushes off the insult. This is not an audience the modern politician dare offend and the result is to diminish the authority of our leaders. Team it with the reflex anxiety over every nuance of polling and we end up with a discussion that is easily mired in misconception and the darker sub currents of the national psyche.

To be reminded of Keating's boldness and certainty is to recall that we have lost more than his trademark arrogant pugnaciousness in the intervening decade. We've also lost political leadership, surrendering it to belligerent ignorance at high volume. You get the feeling that the modern politician, seeing that Keating talkback video would be schooled: "see that's the arrogance that cost him''. And that's cost us.

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