The crisis in Australia’s political system is less about the quality of individual politicians and more to do with the “majority media” and business lobby groups drowning out the independent centre for their own self-interest, distinguished economist, Prof Ross Garnaut has said.

Garnaut, speaking during a panel discussion at the 2018 Outlook Conference in Melbourne, said the big economic reform period of the 1980s came to an end with the rancorous debate about the GST before it was introduced in 2000, “followed by years in which major policy change, reform, in the national interest became rare, more difficult, and temporary”.

Governments since had attempted big reforms, such as the Howard government’s industrial changes, WorkChoices, the Rudd government’s macroeconomic policies to avoid recession during the global financial crisis of 2008, and the Gillard government’s climate policies from 2012, which were working and “would have allowed Australian contribution of its fair share to an international effort without economic disruption or substantial cost”.

All were repudiated, with the “macroeconomic policies that kept Australia out of recession … shouted down by the majority media and the then opposition parties to an extent that will create barriers to Australia responding wisely next time we face recessionary pressures from the global economy”.

Timeline Australia - six prime ministers in 10 years (and five in five) Show Hide Kevin Rudd (2007-10) swept to power in a landslide after 11 years of conservative rule under John Howard. Enjoyed immense popularity as the bookish "Kevin from Queensland … here to help", but after he faltered on climate change (having previously described it as “the greatest moral challenge of our generation”), his convictions were questioned and his administration became increasingly erratic. Alienated his colleagues with an at-times abrasive manner, he was ousted by his own deputy …

Julia Gillard (2010-13), Australia’s first (and only) female prime minister, who narrowly won an election after disposing of Rudd, but was forced to govern in minority. She was remarkably productive given the constraints of parliamentary numbers, passing significant legislation on climate change and addressing clerical abuse, but faced misogynistic attacks from the opposition and was undermined from her own side, led by … Kevin Rudd (2013), who assumed the foreign ministry under Gillard, but never put his field marshal’s baton back in his knapsack. He is widely regarded as having led a campaign of leaks against Gillard, destabilising her. Having failed in one tilt to return to the leadership, he succeeded at his second try. However, he had only three months in the job before losing the election to … Tony Abbott (2013-15), who was widely regarded as the best opposition leader in Australia, but an ineffective and inconsistent PM. His term was marked by an adoption of hardline asylum policies, an abandonment of climate change action, and poor economic management. After a series of gaffes and controversial "Captain’s Calls" (including knighting Prince Philip), he was unseated by ... Malcolm Turnbull (2015-18), a former investment banker and lawyer, who was seen as an urbane, articulate, centrist who could appeal to a broad swathe of the Australian population. But he was mistrusted by the conservative wing of his party, and openly derided by some as "Mr Harbourside Mansion", a reference to his grand house on the opposite side of Sydney Harbour to the PM's official residence. But it was Turnbull’s commitment to action on climate change that incensed the climate-sceptic right wing of his party, and he was stalked by his arch-conservative home affairs minister, Peter Dutton. However, Dutton’s attempted coup failed, and the numbers fell 45-40 for the treasurer … Scott Morrison (2018 to date), who as immigration minister had established Australia’s controversial hardline asylum-seeker policies – including indefinite detention on remote foreign islands. The son of a police officer and an active member of a Sydney Pentecostal evangelical megachurch, he voted no in Australia’s plebiscite on same-sex marriage, listed “church” as one of his interests in his Who’s Who report, and regards former prime minister John Howard as his political inspiration. Howard was prime minister for 11 years – a lifetime by today's standards. Ben Doherty

Garnaut, a senior economic adviser to former prime minister Bob Hawke and author of a landmark review into the impacts of climate change in 2008, told the conference “Australia is in trouble”. A key reason was “a thinning of an informed, engaged, independent centre of our polity”.

“The majority media and the business lobbies have drowned out the independent centre, with raucous assertion of opinions that are convenient to their private interests. The words that are shouted most loudly are now taken by their proponents as facts.”

Most damaging to economic policy was the “promotion of cash-for comment economic modelling, where the truth is incidental to promotion of outcomes that suit the private interests that commission them”.

He said the most obvious examples were climate policy and the taxation of corporate incomes. The result had been community distrust in institutions.

“The loud voices do their best to shout down the institutions that have retained public trust. A sullen electorate is inclined to doubt its political leaders, and disinclined to follow them, both when they are right and when they are wrong.”

Garnaut declined to specify which parts of the “majority media” were responsible. The outlook conference is sponsored by the Australian and the University of Melbourne.

He told Guardian Australia there was a need for a better resourced and competitive media, and there was “a case for fiscal support for smaller voices.”

There was also “a risk of the deterioration going further” with the proposed merger of Nine Entertainment and Fairfax Media.

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During the same discussion, the former Liberal treasurer Peter Costello said the fracturing of Australian politics over the past decade was not the fault of social media, nor the lack of a government Senate majority or increased partisanship.

In three of the four terms Costello was treasurer, the Coalition did not enjoy a majority in the Senate, and the introduction of the GST was bitterly fought by Labor, he said.

“I think it is much more banal than that. The issue is the politicians are just not sure what the change is that they want.

“The 2007 election shook the confidence of the Coalition. After that the Coalition began to query whether good policy really did lead to electability.”

During his time as treasurer from 1996 to 2007, various strands of the Liberal party could unite around an economic narrative, he said. Without it, the party divided on social and moral issues, “because they were the issues that were in debate”.

Costello noted that when Malcolm Turnbull challenged Tony Abbott for the Liberal leadership in 2015, he claimed there was no economic narrative. “I would agree with that, but then I kept on waiting for the economic narrative to come and I’m not sure that it did.”

The chief executive of the Business Council of Australia, Jennifer Westacott, said it was hard to get the sense of urgency for reform, some issues seemed too complicated, and the reform process was “often terrible”.

“The Neg [National Energy Guarantee] was a good process. It was good policy and we still couldn’t get it done,” she said.