The struggle, the old one, the one that resides in the distant history of the 1980s, is over. The new one is upon us. And the new enemy of the people are the liberators of 1994, the standard-bearers, then, of freedom and democracy but, today, the venal plutocrats of Parliament and Presidency. We are going to the dogs.

This, at any rate, is probably how opponents of the African National Congress will read Feinstein's unsparing critique of the ruling party under Thabo Mbeki, and its shameful failure to live up to the ideals of the liberation movement from which it still claims its legitimacy and its mythology.

Such a reading of After the Party, A Personal and Political Journey inside the ANC would not, actually, be far wrong. But it would be wrong, by a subtly important degree. It's a profoundly worrying book, and Feinstein says he meant it to be.

Yet the essential thing about this courageous and outspoken economist, former struggle activist and former ANC MP is that he is not an embittered outcast bent on revenge at any cost, but an activist as idealistic now as he was in the heady days of 1994, or indeed, as he was in the late 1990s when, as chair of the ANC component on Parliament's public accounts committee, he helped lead the most important attempt since the Information Scandal in the 1970s to expose government corruption and examine allegations that its senior figures - and the party itself - earned millions of rands in secret.

The arms deal probe the committee he served on attempted to launch was blocked by some of the most powerful people in the government. Feinstein was axed from his committee post in 2001 by none other than Tony Yengeni, then ANC Chief Whip, and was eventually compelled to choose between truth and lies; he chose truth, and resigned later that year.

After the Party is his riveting story. Tellingly, the first edition of 5 000 has sold out. The second edition is on its way. The closed-door culture of the ANC in keeping public matters to itself has evidently left an ill-informed public eager to find out what the ruling party is trying to hide.

Feinstein speaks much as he writes, with a lucid, passionate intensity, yet without the overweening egotism of the self-professing hero. He is coolly in control of what he means to say, but not without regard for the human scale of the political landscape.

He looks forward with a measured optimism rather than backward with the resentful disillusionment his experience must, on the face of it, permit him to feel.

His disappointment at the ANC government's intolerable failure of principle leaves his admiration of the party's ideals, and his ability to acknowledge its considerable creditable achievements, intact. He is a loyal critic, his idealism, he insists, realisable.

It is the greatest indictment, perhaps, of South Africa's second democratically elected government that even loyal criticism is feared.

Just the other day, on talk radio, a presumably pro-Mbeki caller accused him of being "counter-revolutionary".

"Had I been quicker," he reflects, "I'd have said, I obviously missed the revolution."

Because, he argues, what we have in South Africa today is not the bravely revolutionary politics the struggle might have promised, but "tawdry politics" that is no different from the cynical abuses of power and patronage under, say, Tony Blair's New Labour government.

It would be a crass misreading of After the Party, he insists, to find in it proof of an African or South African predisposition to venality and power abuse.

"I think people should be worried - but also willing to engage. There are some real concerns that have arisen in our democracy and it's only when significant numbers of citizens express those concerns that the government will have no choice but to respond and change those practices."

Feinstein paints a picture of an organisation whose MPs and rank-and-file members feel, out of fear, that they need permission to speak, and ought never to say the wrong thing - in public, or even in the party.

"Down that path," Feinstein warns, "lies great peril. When we feel we cannot criticise those who fought so courageously to liberate us, that's when the very thing they fought for will be undermined. To fulfil their legacy in a sense, we have a responsibility to speak up."

But his book "is not intended as an unmitigated attack on the ANC".

"I try to situate what happened by making clear that it has saddened me that this has become normal politics as it is practised everywhere …" arising in large measure from "the symbiosis between business and politics", a phenomenon he traces to the Margaret Thatcher/ Ronald Reagan administrations of the 1980s.

Thatcher, he notes, "inherited a fairly clean public administration … but through the privatisation process and through her own abuse in some ways … a lot of senior civil servants and senior people in government moved into newly privatised entities which were then awarded government contracts to do the work they had been doing in government, and then, surprise, surprise, made lavish contributions to the Conservative Party coffers.

"That was when this relationship became too close and started corrupting politics, and unfortunately we adopted that very easily. That, for me, is the sadness.

"I suppose there are people who will seize on the book as proof of a predisposition in South Africa or Africa to corruption or bad governance - notions which I find offensive - but that is the collateral damage that will come from telling a story that I think needs to be told."

It needs to be told because "if we take truth out of politics, and there is little enough of it in politics as it is, it would no longer be in the service of the people".

This is a challenge Feinstein addresses less, perhaps, to the ANC and its mostly mum's-the-word, kowtowing legions than to the rest of us voters, who are being deceived and disregarded, who need to recognise they have the real power, and use it.

"We as citizens have a responsibility not just to vote now and then. And just whingeing is not good enough, either.

"I did a reading at a book club recently where somebody said, 'Big deal, we know the arms trade is corrupt, we know politicians are a load of rubbish … why bother?' And I said, for goodness sake, it's our responsibility to ensure the arms industry is not allowed to get away with it and it's our responsibility that we get the politicians we deserve. We can't just sit back and say, well, politics everywhere is rubbish, that's the way it's always going to be! I became very emotional at the book launch in Cape Town because I realised just then how sincerely I felt about doing the things that I do, that I don't want my children to endure these tawdry politics. Future generations deserve something better."

To suggest there is no alternative - especially to modern governments succumbing helplessly to the pressures, and sweeteners, of free-market wheeling and dealing - "is a nonsense".

"I happen to believe in quite orthodox economics, which I got criticised a lot for in the ANC. I was always a great supporter of Gear, for instance, and I happen to believe in the market mechanism as the most effective form of economic organisation that we have managed to establish.

"But within that I believe there should be far greater regulation of the private sector, particularly the gambling, pharmaceutical, arms and natural resources industries.

"It's a question of balance, of trying to find something that's workable, efficient and just. The global economic system focuses so much on efficiency and profitability and forgets about the just, and parties historically of the Left have been far too uncritical of the activities of the private sector."

A regeneration is urgently wanted, and "speaking truth to power" - the phrasing borrowed from Palestinian intellectual Edward Said - is critical to it.

"At my launch, I said where humility is lost and omnipotence assumed, tragedy and failure will inevitably ensue. That's where we are."

But from the powerful elite that is what he deliberately calls "Thabo Mbeki's ANC", Feinstein has heard not a peep.

Although that's not entirely true.

"I had a very funny experience in London recently when the BBC did a programme on the arms deal on Newsnight with me and Alec Erwin (Minister of Public Enterprise). And, throughout, all Alec Erwin said was 'That's not true', 'No, no, that's not true', 'No, no, that can't be true'…

"The next morning our high commissioner in London called the BBC and said the minister demanded the right of reply and he happened to be in London.

"The BBC said, 'Well, how can you demand a right of reply? He was on the programme.' So the high commissioner said, 'He wants to talk about it further,' and the BBC said that would be wonderful and since the minister was in London they could do something that night, and I could appear live with him. Well, they didn't hear from him again.

"They have obviously decided they are just going to ignore me."

Feinstein says that apart from private contacts from MPs and others who support him, he has had no interaction with the party.

At the time of his uncompromising stand in 2001, he was disappointed at the absence of support from senior figures in the party.

"Virtually all senior people closed ranks around the deal, and as I say in the book, the reason for that is that people who were perhaps taking a more dissident stance were informed that the ANC stood to be highly embarrassed if it became apparent that the organisation benefited financially. It was disappointing, but that's not to say there was nobody who supported me. There were a number of people who supported me privately and continue to do so."

One of the most troubling aspects of the politics of recent years has been the decline of Parliament as an institution.

"If you look at the early years, Parliament played a very independent role in holding the executive to account … and that's why I see the arms deal as an unfortunate turning point.

"People saw what was happening, and saw what was being covered up and thought, 'If we want to safeguard our future here we are going to have to keep our opinions to ourselves.'

"So the institution lost its vigour, and that's something that needs to be regained rapidly."

Feinstein says he has at least "a degree of optimism and hope" that the leadership battle will sponsor more vigorous debate.

"I do think Thabo's leadership style has resulted in a negative change in the nature and the values of the organisation, but I nevertheless feel that there are sufficient people of quality and integrity for it to regenerate over time and be the organisation it was in the early years of government, when there was far more open debate, far more collective decision-making and far more integrity.

"I think it will be best for the party if neither Mbeki nor Zuma stands for the leadership, because I don't think they have shown the moral integrity to lead the organisation or the country, but to be quite candid, I think that's highly unlikely. Nevertheless, I do think that down the line, post-December, there is a possiblity that a different ANC, or a grouping in it, will start to assert the traditional values of the organisation again. The divisions won't disappear after December."

It is here, he hopes, that the "incipient roots of regeneration lie".

In the closing chapter of After the Party, Feinstein relates with great poignance the emotional torment of taking a stand, of being "almost embarrassed at the thought of bumping into my former colleagues, as if I had done something wrong, shameful", and "the personal sadness and loneliness of discovering and then publicising that the good guys are corruptible, of experiencing 'the family' turning you into 'the other' for telling the family's secrets in public".

The prospect of "politics of basic truth, honesty and accountability" depends, he writes, on individuals having the courage to "speak truth to power".

With acknowledgement to Cape Argus.