For Gangsta Rap, the year started with a bang. When four teenagers were shot, and two of them tragically killed, at a New Year's party in Birmingham, government ministers and other moral entrepreneurs took pot shots at Gangsta Rap for contributing to 'gun culture' and thus to the murder of Letisha Shakespeare and Charlene Ellis.

   The politicians confused the fantasy world of pop music with the real world: the same failure of judgement ascribed to today's urban teenagers. Yet young people are accustomed to the distinction between fantasy and reality. On New Year's Eve Letisha Shakespeare and Charlene Ellis went out dressed like characters in a Blaxploitation movie. But this was no reason for them to be caught in the crossfire of a real-life shoot-out. They were shot dead in an instance as rare as it is shocking — and neither their dress sense nor their musical taste had anything to do with it.

The main problem with the musical fantasy of Gangsta Rap is not its influence on crime, but that it is neither musical nor fantastic enough. Its imaginative register (sex, drugs and fast cars) is as narrow as its sonic range. Like High School and Heavy Metal, this is a genre characterised far more by repetition than difference.

The combination of grandiose postures (partly derived from Blaxploitation movies), scratching (achieving a particular angsty, alienated sound by winding vinyl records backwards and forwards on turntables), and rapping (talking in metre and often in rhyme) emerged in New York nearly a quarter of a century ago, where it came to early fruition in the work of Grandmaster Flash, and was documented in the film Wild Style (a big influence on various British performers including the Wild Bunch, Bristolian precursors of Massive Attack).

Rap migrated from East to West Coast, to the downside of LA described by Ices T and Cube, and NWA (Niggas With Attitude). Thence, with a different beat, new stars such as Buju Banton and Shabba Ranks, and a new name, ragga, it shifted to the dancehalls of Kingston, Jamaica, before crossing the water to London for another re-mix, this time as 'garage', at the desk of So Solid Crew.

Gangsta Rap has travelled a long way. If only its musical development were as far reaching. Rap was facilitated by digital recording, which enables sampling and thus the construction of a universal palette of sounds even in a bedroom Portastudio of one's own. But, with few exceptions, the use of this multi-faceted instrument has been one-dimensional. Rappers and associated musicians have been so fixated with the rhythm track (drums and bass) and the break (instrumental section) that most have restricted themselves to a meagre, musical diet without the essential protein of melody and harmony.

One of the factors which may have restricted Gangsta Rap's musical growth is 'the tyranny of expectancy' (Gunnar Myrdal's term for white expectations of what black culture should be) and the pressure on blacks to perform accordingly. But whereas Duke Ellington managed to overthrow this tyranny and re-invent jazz, rappers like Ice T can only go through their original motions while parodying them and camping them up more explicitly. Thus last year's folk devil becomes next year's pantomime dame.

Gangsta Rap is as predictable as Snow White and equally camp. Why does the Gangsta Show run and run? Its main attraction is the rejection of respectability, both musical and moral. By parading in the costume of criminality, Gangsta presents itself as the representation of those who are 'other' than mainstream society. But here the pantomime stops. For this is an oppressive condition that is thrust upon black people while being widely imitated yet greatly misunderstood by whites. Half-Spinal Tap, half-LA riots, Gangsta Rap is simultaneously as ludicrous as Ozzy Osbourne and a compelling expression of problems that won't go away: race, the alienation of youth. This combination makes Gangsta Rap a prime target for moral entrepreneurs.

In 1991 when Ice T's 'Cop Killer' was criticised by everyone from Charlton Heston to Jesse Jackson for inciting violence against the police, and again in 1993 when the cover of his Home Invasion album, showing a suburban white kid whose mind had been colonised by black cultural icons, was reviled as ratification of the assault on Western values, there were fears that rap would be marginalised in a 'culture war' that was really about race. The New Musical Express published "a selective guide to the US rap that's currently not available in your high street record shop", and reporter Angus Batey concluded that "political pressures are forcing hardcore rap back underground."

In 2003, by contrast, Gangsta has never been more visible. Days after the Birmingham shooting, respectable film critics were tipping Eminem's movie debut for an Oscar. OK, so he's white. But, alongside police officers and politicians, studio discussions of 'gun culture' featured black djs and record producers, who previously would have been noticeable by their absence.

There is an interface between Gangsta Rap and real crime, highlighted by the murder of three prominent rappers (Tupac Shakur, Biggie Smalls and Jam Master Jay) since 1997. But art, intrigue and murder have been bedfellows since the days of Marlowe and Mozart. The fact that they co-habit does not mean that one is the progeny of the other. You might as well cite the criminal record of the Borgias as the inspiration for Renaissance painting, or indict the Mass as the cultural experience which informs the murderous activity of the Mafia.

Those of us who don't believe in transubstantiation need not subscribe either to demonisation or to the cult of authenticity. The gap between illusion and reality is the unspoken rule of Gangsta Rap and any other cultural form which uses fantasy to comment on lived experience. This discrepancy is well-known to most of its performers and their audience, but not, apparently, to the government ministers who took Gangsta Rap's hyperbole at face value.