The current debates need context. How predictable was the current controversy? Are the Greens behaving differently to other political parties, including previous minor parties like the Democrats? If the Greens have peaked never to recover their momentum because of an alleged combination of extremism and inflexibility then it makes quite a contrast with the demise of the Democrats.

The Democrats, a centre party, did a deal with the Howard government after the 1998 federal election over the introduction of the GST. They could have refused to support it like independent Brian Harradine. Led by Meg Lees the Democrats tried to improve the tax reform to make it fairer and more environmentally- friendly. There was more to it than that, but it was the beginning of the end. Its own supporters were outraged and the general public believed that instead of keeping the bastards honest they had become bastards. The Democrats bargained, as they did on earlier on issues like industrial relations, while the Greens allegedly have not.

Another key element in the demise of the Democrats was that their senators split over the GST. Two future leaders, Natasha Stott Despoja and Andrew Bartlett, refused to back Lees, though those two votes couldn't stop the legislation. Disunity in the Senate and in the wider party dogged the Democrats from then on. In contrast the Greens have not split. One of the predictions as the Greens grew as a party was that, like the Democrats, they might fall apart. That hasn't happened, despite the presence of issues like the carbon and mining taxes and asylum-seeker policy, just as divisive as anything that faced the Democrats. There hasn't even been much speculation of internal division causing voting splits.

There are two elements to the current controversy surrounding the Greens. The first is the party's philosophical position. The main criticism, cynical or serious, by the major parties has been that it is a far- left extremist party with values on the economy contrary to mainstream Australian values. Evidence has been offered that some of the party's personnel, including Senator Lee Rhiannon, are too far to the left and have relations with other groups on the far left. There is no doubting that the Greens hold views on the left very different from the major parties. But their views, taken one by one, are not extremist. Each of their controversial policies has wider support in the community, the left of the Labor party and some other MPs. Whether it is non-government school funding, same-sex marriage, onshore processing of asylum seekers, taxing mining companies, or fighting global warming, the views of the Greens are within the reasonable range of Australian politics, though on the left.

The second element is the party's approach to parliamentary politics. A long-term criticism of the Greens, recently revived following the failure of Parliament to resolve the asylum- seeker processing issue, has been that the Greens are inflexible and unwilling to compromise. Often the contrast has been made with the Democrats, who, it was often said, were willing to negotiate with government to improve policy outcomes. The Democrats were a parliamentary party while the Greens are a social movement. But look where that got the Democrats in the end.

Frustration with the Greens has boiled over because they failed to support the Oakeshott-Labor asylum seeker compromise bill. Mackerras calls this moral vanity or self-righteousness, while also accusing the Coalition parties of hypocrisy. Much earlier the Greens crucially failed to support the final global warming compromise offered by the Rudd government.

But on other matters the federal Greens under Bob Brown have compromised, including on the Gillard mining tax which, along with many others, it thought was pitched too low.

The question should be whether the Greens have compromised/failed to compromise at the right moments and on the right issues. It is ironic that the most inflexible party in the current Parliament has been the Coalition, led by Tony Abbott. It was Abbott rather than Brown who earned the nickname Mr No. If the Coalition had compromised with the Labor government over asylum-seeker processing the question of the Greens' stance would have been quickly forgotten.

Politics is not just about the art of compromise but about the combination of compromise and standing firm. As a community we value both attributes. In fact in the recent past lots of praise has been given to so-called conviction politicians compared with others who flip-flop or don't have firm values. John Howard was one who, like Brown, was singled out for having that attribute. Whereas Howard actually had both and was willing to deal, as he did with the Democrats, or shift positions as he did when challenged by Mark Latham on parliamentary superannuation. He even tried, too little and too late, to compromise on Work Choices, the policy that brought him down.

''Politics is the art of the possible'' should not be interpreted as always valuing compromise over steadfastness. All parties, including the Greens, face such choices. The Greens should search their souls on getting this balance right. But getting the balance right between flexibility and knowing what you stand for is a lesson that Labor and the Coalition should study too.

John Warhurst is an emeritus professor of political science at the Australian National University.

John.Warhurst@anu.edu.au