Artists have been responding to the war in Iraq since the build-up in 2003. Memorial to the Iraq War, the exhibition opening at London's ICA this week, is only the most visible manifestation of a whole matrix of works, actions and protests over the last few years. The problem is that many people, artists included, feel increasingly trapped between extreme forces of ideological perversion.

Superficially, contemporary art is not well placed to confront the recent clarifications and extremes of conflict in a direct way. This explains why there has been little collective response independent of the anti-war movement in general.

Much postmodern theory was based on how to understand a globalised environment of relativism, subjectivity and simulation. We are now facing a situation of specificity and desperate rationalisation in Iraq and elsewhere. Art became more and more diverse throughout the 20th Century. The Iraq war is an example of one of the many clarifications that may appear to render art more and more irrelevant. The US army has reconvened and prays to its God for strength. The factions in Iraq pray to theirs. Everywhere we see routine obscenity.

For artists, the combination of piety and pragmatism from politicians on all sides is not worth showing back to them. Documenting the increasing piles of body parts is pointless pornography. What artists can do is occasionally step outside their normal practice and stand as citizens against the delusions of their leaders. This is an exceptional moment, where it is necessary for some to suspend their normal work in order to make a direct statement.

In this context, the ICA exhibition is not an answer; it is a melancholic and sullen response. The idea of creating a memorial to something that is still taking place is an honest concession. It is no good looking back to some earlier moment of apparent cultural consensus. We have to look instead towards art as a carrier of differences and a perfect form for the revelation of paradox.

If we attempt to use cultural work as a way to understand a society, we see a true response to this stubborn and pointless war. A multiplication of differences, subjective voices, different methods, varied levels of identification.

But beneath it all is an increasing acknowledgment that we cannot accept the routine killing of people and suppression of understanding for the short-term gain of one superstition over another, expressed in apocalyptic languages that mask the politics underwriting carnage.