Power is everywhere. Page after page devoted to the word in the Oxford English Dictionary starts with the simplest definition: "ability to do". Power is an advantage of some kind that helps get things done. The banker David Gonski talks of "fragments of power" exercised by people at every level. He laughs. "If I'm the head of the handicapping department of the golf course, I'm a very important person."

Gonski is a good deal more than that. The chairman of Investec Bank, the chancellor of the University of NSW, arts patron and government insider is an intimate of power. His analysis of how it operates in Australia acknowledges the old fundamentals: wealth, access, background and education. But he believes power no longer operates as it once did. "Power in a modern society is more under check than potentially it has ever been."

Favours are not as easily done these days. "Things are very open and I think that's a good thing. Whereas maybe 200 years ago you could look after your mates if you were in power, today, there is a test: will it be on the front page of The Sydney Morning Herald?"

We are sitting in a room at Investec. A steward has brought coffee. The staggering view of the harbour comes with an invisible but mighty price ticket. Power in Sydney may have begun "out of the barrel of a gun" as chairman Mao observed. But the city has since been fundamentally fashioned by the power of money.

Gonski does not deny the raw clout of money but wonders if that is shifting, too. "There is no doubt money can allow one to do a lot of things but does wealth give oneself access to more than other people? That's actually a very big question. In the past it probably was right because you could get better advice. You could find out more. You probably were more educated. But I just wonder whether that is the case today."

Gonski argues money no longer buys privileged access to knowledge as it once did. He talks of modern technology – particularly the internet – breaking down "knowledge structures". What once only money could buy is now only a few keystrokes away. Gonski argues that scrutiny, easy access to information and a general quickening of the pace have changed how power operates. "Things are much more short term and much more open and that applies to power at all levels."

There is a great taboo in Australia about owning up to having power. Gonski puts this down to living in an egalitarian society: "We want to be the same as the next person so we don't want them to feel intimidated." But exempt from that iron rule are preachers, who claim powers from above, and politicians, whose authority comes from below. "I've got to say, power is fun," says Bob Carr. Not everyone's idea of fun, perhaps, but certainly his. Over lunch in his Bligh Street office – no longer the great harbour view of the premier, but still a view of money – his mind goes back to the day demonstrators opposing workers compensation reform were blockading Parliament.

"Moments like that you know you've got power. I'm in Parliament House; there are no lights on; the staff has walked out; I get a tin of cold baked beans from the fridge to have for lunch. My caucus is at Governor Macquarie Tower and I'm on the phone to Whelan, the leader of the house, saying, 'Paul, if they're not up here, if they don't walk through that union blockade, what happens in the Parliament this afternoon?'

"And my somewhat nervous caucus walked up Macquarie Street, some of them sort of staunching tears, went through the demonstrating building workers and they walked in. At the caucus meeting, I had to get up and say these are the reasons we've got to reform this system and defied them to vote against it. We got it through and then presented it to the house that afternoon. That is fun."

Carr doesn't deny the rich have clout but argues they do not always get what they want. "Alan Bond, one of Australia's richest men, wants permission to throw up Australia's tallest building. He had acquired a site diagonally opposite the Town Hall. The Labor government didn't give him that building. So how does your idea that governments always cave in to the rich stack up?" Carr can talk. Everyone I approached to discuss power in Australia agreed on the importance of eloquence, of the gift of the gab. Those who can persuade, charm, menace and amuse have a power that is absolutely native to them. Gough Whitlam remains Carr's great example of power exercised through compelling advocacy. "Whitlam will go up in historic estimation, given how the Labor Party's capacity to advocate and urge change has fallen. Why were we all drawn to Whitlam? Frankly, because he was a terrific speechmaker. He could put a case. One of the reasons for Labor's predicament now is that we have leaders who can't put a case, just can't put a case. If you can't win arguments – in parliaments and in the media – power ebbs from you."

So who runs Australia? "I think the federal cabinet and the big investors, plus media chieftains and trade unions all subject to the ferocious corrective of public opinion," Carr says.

Power in Canberra is uniquely contested now: a minority Prime Minister stands very low in the polls relying on her formidable powers of persuasion to hold the Labor government together. But Julia Gillard still has the authority of her office. "The power is constrained," says Robert Manne. "But I don't think you could ever make a case that the Prime Minister isn't the first or second-most powerful person in the country." Close to her Manne puts Rupert Murdoch.

The exercise of power in Australia has been the fundamental subject of Manne's work as a commentator and historian. He has no doubt money remains, as it has always been, a source of power. "If anything over the last 30 years, things have fallen the way of the wealthy." And he doesn't write off old families. He notes that a Baillieu is Premier of Victoria and a Forrest is the richest man in the country. They have had to work for what they have achieved but their background counts.

"Every year clearly the most powerful Australian – and I still call him Australian – is Rupert Murdoch, who is from an old family but he has turned that family into one of the dominant families of the world."

Manne and Gonski see eye-to-eye on a number of the subtleties of power in Australia. They agree on the rather overlooked power of families. "I think that you can get opportunities from where you come," says the banker. "If you are from a well-known legal family the chances of you doing well in the law are probably greater because you've grown up with it." The same works for a family of blacksmiths. "It's inheritable and it's also by osmosis. You see how your father or your mother – or both these days – react to things and so on."

The second is the crucial role judgment and trust play in conferring power. "Judgment is one of the least analysed, most important aspects of human relations," says Manne. "If someone appears to have good judgment then a sort of power will come to them because people will listen to them and take very seriously what they say about a situation."

Gonski puts it this way: "All of us in life search for people that we can not only confide in but we can trust. If someone that we believe we can trust urges us to do something, chances are we will do it." It's not necessarily a question of affection. "The powerful duopolies of a great prime minister and a great treasurer were built on trust and often died on lack of trust." And yet they could hate each other's guts? "Sometimes in life – you must have met these people, I have – there are people you really don't like but inherently you know what they're saying is true."

But on the role of networking Gonski and Manne stand far apart. "I think networking is absolutely fundamental to those who wield political and economic and perhaps cultural power," says Manne. "They connect to each other, they talk to each other all the time and can ask favours of each other and, sure, expect favours in return.

"I think a very important aspect of power is the ability to contact someone and to be answered immediately and probably the single best test of who is most powerful is whose message will be answered instantly by the largest number of people."

Then there is the media. Carr says: "If you're writing about power, you have got to write something about the power of the tabloids." Bearing the scars of brawls over a decade or more with Sydney's tabloid radio and newspapers, Carr cites as evidence of their power their capacity to skew state budgets. "If they're running a very angry law-and-order campaign and there's money available in the budget for a new initiative, then that year you'll have more police rather than more child protection workers."

Has he heard it said that the purpose of the tabloid press is to persuade the working class to vote Tory? "I haven't heard it but I think it's incontrovertible."

Manne sees far bigger issues at stake. "Dictating the terms of discussion for the great bulk of society is the greatest power of all, in a way. I more and more see the media as doing that. I give a kind of extreme example: if you take climate change seriously and realise that coal is by far the most important contributor to greenhouse gases in the world and if you see that Australia is an important exporter and relies on coal for 80 per cent of its own energy – then I think it would be completely reasonable at present for us to be debating what we do about the coal industry, whether we begin to phase it out.

"But it is completely unthinkable that that should be discussed. If anyone put up their head to say it they would be shouted down first by the media – first by the commentators – and then later on by the politicians. This is an extreme example of what I mean by controlling what counts as commonsense, which I think is done by the aggregate of media power."

Manne sees Murdoch as the paradigm. "There are two ways of misunderstanding him. One is to think he is only interested in money. The other is to think he is only interested in power. I think his genius is that he is both and he sees the ways massive amounts of money can influence the political agenda – by creating Fox News or various newspapers or Sky television – and they can in turn make money. So he advances a political agenda while simultaneously making fortunes."

Murdoch is under public attack on all sides in Britain for the misuse of power. Literature is peppered with warnings about its exercise. Power corrupts, of course, according to Lord Acton. Abraham Lincoln said: "Nearly all men can stand adversity, but if you want to test a man's character, give him power." Gonski concedes power can, at first, be damaging. "Often when people first get power they're quite excited about it and it affects their humanity sometimes. I've seen people get divorced because they feel they're so high and mighty that their partner hasn't kept up with them and so on.

"But the interesting thing is when they actually get there – if they do and not many do – there's a mellowing, undoubtedly a mellowing."

He puts this down to the breadth of thinking that comes with not being so preoccupied with the climb to power or worried so much with what those above you are thinking. "My experience is that as people climb the tree of any profession, quite often they are much finer at the top than the people as they climb up." He speaks of those he deals with at the very top as "extraordinary people".

Carr backs Lincoln. So what did he discover about himself when he came to power? "I was pleasantly surprised by having a very high stress tolerance. And I was too busy to be anything other than forgiving. "You can't dwell on grievances. There's too much pressure to move on to the next challenge because the agenda is so crowded. It's actually good for your character."

And giving up power? "There is some pleasure in giving it up and finding you're not pining for it, that you can find things to fill your life without it. I think that's the quieter satisfaction that comes in making that transition. You didn't need it."

That's Carr in Roman mode. The lesson of history is the extreme lengths we go to as a species to hang onto power. Once we have it, life without power can seem unimaginable. In the end, it's only human.