At the end of part one of Stephen Soderbergh's immense movie biography, Che, the audience at its London opening yesterday applauded, and some whooped.

I don't think Soderbergh, the occasionally demanding auteur, was the whoopee, but rather the long-dead revolutionary himself. For Soderbergh's Che Guevara is heroic, determined, paternalistic, idealistic, humorous, outspoken - a father-doctor-lover-warrior combination to excite all but the feeblest pulse. If he has a problem it is his obstinacy in smoking cigars despite being an asthmatic. True, in the movie he executes a couple of criminal wretches when he is in the Cuban forests, but it is wartime and their crime was rape, and in movies rape can only be punishable by death. It was interesting that while the audience laughed at the condemned rapist wanting more rum, they went very quiet when the unreconstructed Che used the word maricón (faggot) as a term of abuse. Death yes, homophobia no.

Che, however, used to execute non-rapists too. In January 1957, up in the hills, for example, he shot Eutimio Guerra in the head with a .32-calibre pistol for being suspected of passing on information, and a campesino by the name of Aristidio, for cowardice. This was confided in his diaries. One not unsympathetic biographer remarked that Che liked to see whether condemned men met their deaths with courage, or like a maricón.

Once the revolution in Cuba was won - 50 years ago in January - Che took command of the military court convened at La Cabaña fortress in Havana, and processed the death sentences of dozens - possibly hundreds - of prisoners after the most cursory of trials. A left-wing Basque priest officiated for the condemned. “I pleaded many times with Che on behalf of prisoners,” he said later. “I remember especially the case of Ariel Lima, a young boy. Che did not budge.”

These semi-judicial murders were only one part of Che's implacability. At the time of the Cuban missile crisis in 1962, Che was prepared to countenance a first nuclear strike by Soviet missiles against the United States. One can imagine that it was with some relief that Fidel Castro saw him depart for Bolivia and oblivion.

The point is that being heroic is not, in itself, a cause for celebration. It can be quite the opposite. This was suggested to me again by a review of the new film Hunger, which opens this week. Hunger deals with the republican hunger strikes in the Maze prison in Northern Ireland in 1981, in which ten IRA and INLA prisoners fasted to death. The reviewer writing in The Guardian was Ronan Bennett, a former republican prisoner, now a much esteemed novelist and playwright.

The film's main character is the IRA man and Sinn Fein MP, Bobby Sands, and the film-makers have captured “Sands' unsentimental idealism, resilience and determination”, “allowing him to emerge undiminished in body or spirit”, in the “simple recognition of his full, complex humanity”.

But what would any of this avail us if Sands's cause was a bad one? Heroism is not confined to the virtuous - ask former members of the Waffen SS. Here Bennett lauds the moviemen for permitting “what is implicit in each scene to emerge unforced and unstressed...[and throwing] us as viewers in at the deep end, trusting that what we see will eventually make us understand”, but admits somewhat contradictorily that “the emphasis is on the State as the perpetrator of violence and on republicans as the victims, something the 100,000 people who lined Sands's funeral route would have had no trouble in recognising”.

Sands died on May 5, 1981. The second hunger striker, IRA man Francis Hughes, died exactly a week later. I am sure he would also have possessed a complex humanity. Hughes's problem - unexplored by Hunger or Bennett - was his habit of depriving other people of theirs. To take one example, on February 8, 1978, William Gordon, part-time soldier and school welfare officer, was, as on every weekday morning, driving his son and daughter to their primary school. Presumably this pattern was known to the IRA team led by Hughes, which planted a bomb under Gordon's car. The seven-year-old boy was blown clear, but badly injured. His father was killed instantly, his ten-year-old sister decapitated.

This one example will do. Between 1969 and 1999 thousands of British citizens were killed, the large majority by republicans. And this is Bennett's political judgment on the importance of Sands (and, presumably, Hughes) that he “probably did more to turn the tide of the republican struggle than any other individual. His death garnered worldwide attention and sympathy, and it marked the beginning of the long run of electoral successes that eventually propelled Sinn Fein into government”.

In other words the IRA changed strategies, winning its goals through an increasing use of political rather than violent means. So, in a way, it was all - though horrible - worth it. A new book, Gunsmoke and Mirrors: How the IRA Dressed up Defeat as Victory, by the Observer journalist Henry McDonald, explicitly challenges this self-exculpatory mythology.

Sands's death came 12 years into the Troubles and 13 years before the first ceasefire. His funeral orations and those for his fellow hunger strikers helped to recruit a new generation of benighted bombers and shooters. What eventually forced the change of strategy on the IRA was not the success of the ballot box, but the defeat of the Armalite. McDonald argues that the key year was not 1981, but rather 1987 when one unit of the IRA was rubbed out by the SAS in Loughgall, and when an IRA bomb on Remembrance Sunday in Enniskillen caused international outrage. It was in this year, points out McDonald, that Gerry Adams made approaches to Charlie Haughey, the Irish Prime Minister, about charting a new course.

In the end Adams and Martin McGuinness - brave though they have been - achieved for themselves no more and no less than a peaceful civil rights movement would have achieved ten years earlier and with 3,000 fewer deaths. It is this that republicans cannot bring themselves to admit, and that the mythologists want to obscure.

Also showing this week at the London Film Festival is a new German film about those other armed rebels, the Baader Meinhof gang. I think Ulrika Meinhof probably possessed qualities of idealism, resilience and determination. Just like Sands, just like Che. It should remind us that, with nothing certain and a world recession on the way, this is a bad time to be lauding bad heroes.

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