Cultural concepts go in and out of style, sometimes quite swiftly. It was fashionable a short while ago to proclaim we had entered an age where the old cultural certainties had been thrown into disarray; it has become just as fashionable now to dismiss the postmodern as yesterday's news. Recently, I had to write a dictionary entry on 'post–postmodernism', a term which certainly communicates a desire to put postmodernism behind us. I don't think this desire is justified. Furthermore, I would contend that far from being over, postmodern theory is needed more than ever.

Let's start with fundamentalism. Religious fundamentalists have barely come to terms with the modern, never mind the postmodern. For many of them the ideal is a pre–modern world, either literally as with many Islamic extremists, or in terms of our moral and sexual behaviour — witness Christian fundamentalism and the 'Silver Ring Thing' project. The Enlightenment may as well never have happened for these groups, who look backward nostalgically to a day when religious authority went unquestioned and everyone lived by the book — the Bible, Koran, or whatever.

However optimistic the vision in historical terms, it is clear that the Enlightenment offered a concerted challenge to this assumed authority. When Enlightenment principles themselves hardened into dogma, postmodernism took over as the dissenting voice.

Like their Enlightenment forebearers, postmodernists went beyond religion to cast doubt on all forms of authority, instituting a valuable internal critique of the western political process. Above all else that is what postmodernism is: a critique of authority. And critiques of authority are what our current world order desperately needs. The postmodern is a state of affairs; postmodernism a theory about that state of affairs. One could be drawn to the former while rejecting the latter.

Postmodern theory has alienated even those who might agree that modernity is in need of a rethink. New Humanist contributor Francis Wheen includes postmodernism in the species of 'mumbo–jumbo' that he argues has come to exercise such a hold on the public consciousness; no better than astrology or any of the pseudo–scientific or religious cults preying on the gullible. Admittedly, postmodernists can be their own worst enemies, presenting their ideas in stilted language and making wild claims about how much the world has changed: the 'grand narratives' are dead, no–one trusts authority any more, all authority is intrinsically authoritarian. Yet even a cursory glance around us would suggest that we have not left the modern behind yet. Nor have we left the pre–modern totally behind either: fundamentalists are doing their best, by prohibition of various activities, to return us to that condition. Even Wheen would have to concede that postmodernists aren't oriented towards prohibition. Neither are they claiming to have discovered 'the truth', or 'the book' all the rest of us must live by.

The postmodern and postmodernism can be linked. I see the latter as a theorisation of what is happening in society at grass–roots level, rather than an imposition of high–flown theories from above on an unsuspecting public. The latter is the line frequently heard nowadays, with figures such as the late Jacques Derrida targeted as culprits (despite a resistance to being classified as postmodernist). But Derrida and company did not create the suspicion of authority that has come to be such a feature of western life; they tried to construct theories for it. Whether their interpretations are right or not, the suspicion remains.

Meanwhile, fundamentalist elements in the ecology movement hark back to a pre–industrial age, when humankind was assumed to be in harmony with nature. This is nostalgia on a grand scale, and postmodern irony is the most appropriate response. Postmodernists do not believe in golden ages; instead, they emphasise the constantly changing pattern of events and the openness of the future. From this perspective nothing in the past binds us, no doctrine has the right to dictate our behaviour generation after generation. The major Enlightenment thinkers espoused just such ideas, so it is disappointing to find them under threat again over two centuries later. For fundamentalists and dogmatists, however, pluralism is the enemy and anything less than true belief is unacceptable.

Pluralism is often attacked as a byword for anarchy; an 'anything goes' approach to ethics and politics. Postmodernists are relativists, and relativism can be characterised as intellectually irresponsible. But relativism isn't the world's major problem right now; true belief is. Postmodernism asks us to suspend our sense of certainty; to move away from zealotry. If it makes ethical decisions more problematic, that seems a small price to pay for protecting us against the excesses of true belief. We're far more at risk from those who know the answers to all political and ethical questions than from relativists and pluralists.

The postmodern still matters. We should avoid falling into the trap of thinking it was merely a short–lived trend we can safely dismiss, like some disposable item of popular culture. Postmodernism's commitment to dissent, pluralism, and cultural diversity is needed more than ever. Forget the fashion arbiters, this cultural concept has by no means outlived its usefulness.