No big prizes for working out why Argo won the Oscar for best picture this week. It is a superb movie – clever, witty, beautifully paced, brilliantly acted, exciting, suspenseful, characterful etc, etc … And, of course, it's based on the true story of how CIA agent Tony Mendez (played by director Ben Affleck) put together the "Canadian Caper", in which he faked the production of a sci-fi movie in order to rescue six US diplomats from Tehran during the 1979 Iran hostage crisis.

So, crucially, it tells Americans something great about themselves – about their courage, their ingenuity, their audacity and the lengths they will go to in saving the lives of other Americans. Just what the doctor ordered, at a time when the US has cause to feel a little less bumptiously certain about its global supremacy.

However, Argo, despite its many wonderful qualities, would be just another technically proficient pile of steaming horseshit if it wasn't for the opening sequence, which uses historical footage and cartoon storyboards to make it abundantly clear that the Iranians had every right to be furious with the US, and to blame America for its woes. It's all there – the US's arrogant, self-interested, ruthless, hypocritical, unforgivable meddling in the sovereign affairs of another state, prompted by the UK and Churchill during and after the second world war, and up until the present day. Affleck is an intelligent man and a shrewdly commercial film-maker. He doesn't offer the US more truth than it can bear. He refrains from overdoing the mea culpas to the point at which Americans would reject them. Affleck doesn't sugar a pill, he "pills a sugar".

It's useful to compare and contrast Argo with Kathryn Bigelow's Zero Dark Thirty, about the hunting and killing of al-Qaida leader, Osama bin Laden. Zero is a much more demanding, complex and uncompromising film, far less easy to slot into the Hollywood thriller genre, and overlooked at this year's Oscars, apart from half-a-statuette for sound editing. Zero Dark Thirty has, of course, been highly controversial. There's a lot more pill than sugar in Bigelow's movie, that's for sure.

The pill, of course, is the torture. Critics from the left argue that the film glorifies torture by suggesting it's a useful way of operating, even though it was not used to make any of the specific intelligence discoveries that led to the assassination of Bin Laden. Critics from the right simply don't like the fact that the sort of torture the CIA resorts to has been depicted in a Hollywood feature at all, even though they strongly defend its efficacy in "real life".

You could, of course, be strictly pragmatic and condemn Zero Dark Thirty because it placed the needs of a film script above the integrity of the pertinent historical fact underpinning individual stories. But Argo plays extremely fast and loose with historical truth as well, grossly downplaying Canadian involvement, portraying Iranian officials as childish and easily duped, distorting the rescue mission to make it seem far more nail-bitingly precarious and in-the-nick-of-time than it actually was. What's the difference? Why is one historically inaccurate film about US involvement with the Middle East dismissed for the artistic licence it has taken, and the other garlanded when it has taken similar liberties?

It's simply that one film's overall message leaves no room for ambiguity in its portrayal of its hero, while the other, on the contrary, introduces very dark moral ambiguities that it needn't have. Affleck sacrificed accuracy in favour of easy-to-swallow heroics. Bigelow sacrificed accuracy in favour of hard-to-swallow anti-heroics. Argo's infelicities are conventional, clearly undertaken in the service of creating a recognisably feel-good cinematic narrative. Zero Dark Thirty's infelicities are much more difficult to read, as can be seen from the touching union between left and right in despising it.

In the end, however, the right understands better than the left that no one who is depicted as a torturer ever ends up entirely "glorified". That's why they prefer total secrecy and lack of acknowledgement around such matters. The torture sequences at the start of Bigelow's film are most usefully viewed as similar in intent to the potted history of US involvement in toppling the democratically elected leader of Iran, and replacing him with a decadent and authoritarian Shah. Both warn: "This is the story of an individual CIA agent's success – we're celebrating that. But it's part of a much more dubious wider context, of brutal and ignominious manipulation. That's not so easy to celebrate."

Both films would have been more existentially "inaccurate" without their early contextualising scenes, in which Americans are portrayed committing acts against foreign states or foreign nationals that they would not tolerate being conducted against their own. Without those scenes, both films would have been simple glorifications of individual CIA agents battling against the bureaucracy of the CIA as a whole. Affleck just slapped on his rider in a less contestable, less visceral way, which was more acceptable to the audience.

Yet it's fascinating, the way these two film-makers have both chosen to make films that denigrate the CIA as a whole, yet venerate lone operators within it. Overall, both films say that whatever shortcomings the American state may have, it still produces exceptional individual Americans. Actually, any culture can and does produce exceptional individuals. One of the great things about the US is that it unashamedly gets behind such people, nurturing "the gifted" in a way that Britain shrinks from doing.

But America's insistence on believing that somehow the particular qualities of the US as a state – good and bad – are indivisibly and uniquely brilliant at producing exceptional people is mistaken. Above all, it stops the US from really grasping that its empire-of-influence attitude to the rest of the world is hugely damaging – both to non-Americans and to the standing of the US itself.

Somehow, the US is always making an invisible movie about itself, an endlessly refreshed and recast mythology in which the nation itself is a doughty individual going against the grain and always certain that, whatever the risks, it will be proved right in the end, the story of its individuality and heroism only burnished by the surrounding recalcitrant nay-sayers. The US likes Argo because it sticks more closely to that line, while displaying a bit of doughty individuality itself.

It's wary of Zero Dark Thirty because it deliberately blurs the line. It may be suggesting that even doughty individuality isn't necessarily a justification, an excuse or a worthwhile undertaking when the violation of the rights of other humans is being undertaken in its service, however crowned with success those individual efforts may be. It may be suggesting the opposite. That's not the important thing. You leave the cinema after seeing Zero Dark Thirty feeling troubled. You leave the cinema after seeing Argo feeling thrilled. Argo may be a more entertaining film. But Zero is disturbing, serious, doughtily individualistic art.