Howard Jacobson: If the Coens were going back to their Jewish roots, they must have lost their way

They are now the quintessential unfeeling geniuses of our time

I've an equation for you. Call it my contribution to the great "What is art/What is beauty?"debate which the BBC has been fostering these last few weeks. A-H=Af. Art minus Heart equals Artifice.

I hit upon this equation while watching the latest Coen Brothers movie – A Serious Man. It will tell you something about the film, or at least my reaction to it, that I could take time off from the visuals to do algebra. M-I=Ad2. Movie minus Interest equals Attention Deficit squared.

In fact that's not true. The film didn't fail to interest me. Everything the Coen Brothers make interests and intrigues me, allowing that you can be interested and intrigued and still left indifferent in your soul. Watching a Coen Brothers movie is like being impaled by an icicle. You sit transfixed and frozen.

Fargo was set in the snows of Minneapolis so that we shouldn't mistake the message. Whenever snow claims a life in film or literature I think about Gerald Crich in D H Lawrence's Women in Love, trying to master the cold, stumbling "in the bluish darkness, always climbing, always unconsciously climbing" up the fallen masses of black rock. But this is Alpine snow, a heroic setting for a futility which breaks the heart. Tragic snow. That's Lawrence for you. But the Coen Brothers don't do tragedy. They do sadistic farce, which is something else.

The sadistic screw-turning felt tedious the second time I saw Fargo, its elegant, grand-guignol nihilism as cheaply bought as any naughty installation by those other Brothers in cynicism – the Chapmans. And when I went the third time, just to be sure, I was repelled. Once you stop being amused by the corpse going into the wood-chipper you're in trouble. So don't watch movies three times? OK, I won't again. I found it hard to get through No Country for Old Men once. The fact that critics drooled over it only proves what a mess the movie business is in. In movies, as in the art that excites Tate Modern and excited (sometimes) the judges on BBC2's School of Saatchi last week, a little irony goes a long way. You can see why. As an antidote to the oily sentimentality in which our culture fries us, a little dry irony settles the stomach. But in the end an ironic unremitting bleakness becomes just as routine as the cheery optimism it mocks. Nothing in art works if it is just itself. Art needs to be in an argument. A-Arg=P. P standing for Predictability.

I had high hopes of A Serious Man, hyped as the Coens going back to their Jewish roots. Art-hopes not ethnicity-hopes. Just because I have sometimes revisited my Jewish roots myself doesn't mean I can't wait for every other Jew to do the same. Up to them. There's no obligation. But I was curious to see how the Coen Brothers' minimalist irony would stand up to a culture which is anything but minimalist or ironic. I'm not saying Jews can't do irony, but it is not their natural medium. Jews like more not less, words not silence, sun not snow. Rothko's the exception that proves the rule. Philip Glass ditto. But then there's that austere prosaist Philip Roth, who is not averse to schmaltz in season – schmaltz being to irony what a cross made of garlic is to a vampire. Could the Coen Brothers find the schmaltz they have spent their careers shoving into wood-chippers?

Alas, no. Not a teaspoon of it. What they found instead was a biblical superstructure with which to coat the same old sardony. This was Fargo and No Country for Old Men rolled into one, with the Jewish God Hashem playing the villain. Been done before, of course. The last time it was called the Book of Job, which on balance had a few more laughs. And was certainly more of a contest. In A Serious Man the Coen Brothers weighted the scales as they always do, liking nothing they saw along the way – neither Hashem himself, nor any of his hapless victims, and least of all the planet with which the Divine Malignancy toys.

I'm OK with not liking. I'm even OK with not liking Jews. Some of my best friends etc, and some of my favourite literature. Jews aren't the be all and end all. You don't have to like them. You don't have to like anybody. Men/ women, straights/gays, God/the devil – in art you can hate the lot. But there is something retarded at the heart of not liking when it targets the obvious. Living in this country at the height of Blair-baiting was like living in one giant fourth form. Listening to atheists is the same. It isn't that they're wrong, it's that they haven't moved on from the disillusionments of adolescence. Politicians lie, God isn't very nice. Get away!

I'm not complaining on religious grounds that the Coen Brothers mock rabbis the way we all mocked rabbis when we were 13. So the Coens look without pleasure at every aspect of Jewish life – so? I had the same charge levelled at me after my television series Roots Schmoots. Didn't I know a nice Jew? Couldn't I find a Jew who didn't look so ... Jewish? I felt similarly watching A Serious Man. Did they have to look so ... Jewish? But the complaint makes no aesthetic sense. You see what you see. Misanthropy is art's prerogative.

But coldness is something else. Coldness is artistic arrogance. It is a refusal to engage in an argument with warmth. The vogue for irony in art and film is a reaction against an excess of feeling – too much emotionalism, too much sploshing on of colour. Art changes, as art must change, by one age refuting the assumptions of another. But the rejection dare not be too wholehearted and the victory dare not be too complete. Artistically bored by the scale of his success as an installationist, Damien Hirst is now desperate to paint. It is as though he has joined forces against himself and become an artist – not by virtue of the paint but by virtue of the quarrel.

The Coens had the opportunity to join forces against themselves this time round. Let in some discord. But they blew it. Maybe their being brothers is the problem. Maybe a brother mirror-images you, offering only the illusion of creative division. Whatever the explanation, they are now the quintessential unfeeling geniuses of our times, doomed to the heartless logic of their own smooth artifice. I never expected to hear myself say this, but it would seem you can have too much art.