Not since the fall of the walls and the demise of the Soviet Union has censorship been so much in fashion. Gone are the old clarities of the Cold War - they censored, we did not - to be replaced by an infinitely more complex and shifting map of censorship.

In one sense, it is only the geography that has changed; in another, all is much as before. There are still plenty of autocratic or more overtly dictatorial regimes around the world in which the media and other forms of public expression remain firmly under the control of ruling cliques and their sympathisers, while in much of the post-communist world the media and the arts find themselves once again confronted by old-fashioned forms of official censorship as well as by the more recently discovered dictatorship of the free market. In yet other places, nationalism and religion have replaced political ideologies as the shock troops of silence. Most notably, the beast of censorship has merely donned new clothes and slouched off westwards to take up residence among its former enemies. It is this slide to the west, specifically to the USA, that preoccupies Robert Atkins and Svetlana Mintcheva, the editors of Censoring Culture. They are right to be concerned: the 'culture wars' of the 1980s and 1990s, which were largely concerned with the battle over public funding of the arts, have extended their reach into every corner of the cultural field, from publishing to the Internet, from politically charged exhibitions and events in privately funded spaces to the portrayal of sex and violence in film and television. As the editors point out, none of the arguments overtly advanced to stifle expression are new: the protection of children, respect for religious and cultural beliefs and sensitivities, the desire not to offend racial or sexual minorities. Moral panic is as strong as ever and while the politically correct speech codes of a generation ago may be less in evidence on the campuses of the US in the wake of 9/11, subsequent events in the Middle East and the 'war on terror', 'hate speech' – the expression that offends – exercises a chilling effect on all forms of potentially offensive or controversial expression. The instinct in the land of the First Amendment, it seems, is to silence rather than engage with debate or controversy. The more we read, the more appropriate it seems to talk of a culture of censorship rather than the censorship of culture.

And behind these familiar and tangible social, political and cultural mechanisms that seek to limit free expression are the less visible but more powerful economic realities of the market place: the power of money. This is most evident in the communications and publishing industries, and André Schiffrin provides a cogent analysis of the ways in which corporate mergers and monopolies in the latter have drastically curtailed the range of literature available to a reading public. In the arts world, too, fear of losing a private benefactor or public funding in these more sensitive times ensures the de-selection or dumbing down of exhibits that might provoke controversy.

When it comes to the Internet, the ultimate victory of the market is far from assured. This is one of the less satisfactory sections of the book. The web is a fast moving and flexible medium; much that is written here has already been overtaken by events. The outcome of the guerrilla war that rages back and forth over free use and free expression in cyberspace is by no means as cut and dried as the editors imply.

Censoring Culture concludes with a number of reflections on self-censorship. As the editors admit, this is the least explored of all aspects of censorship yet they do little to further our understanding. It's a tricky – not to say sensitive – subject that we need, nevertheless, to get to the bottom of if we are to make sense of what is going on in the US. We can never know what might have been said in a world free of censorship, but as any writer or artist who has lived under a draconian censorship regime will admit, the ultimate triumph of censorship is self-censorship: the self-preserving complicity of the author. As the South African writer JM Coetzee says here in a brief and moving contribution, "The censors edict, or the internalised figure of the censor, is [not] the sole or even the principal pressure on the writer: there are forms of repression inherited, acquired, or self-imposed that can be more grievously felt… the obstacles that writers are capable of visiting on themselves are surely sufficient in number and variety for them not to invite more." It is evident from what follows that US writers, artists and curators are also aware of the pitfalls of self-imposed silence; equally evident from the evasions, omissions and justifications that characterise their conversations that this is the sin that dare not speak its name.

And there the discussion ends. So much for the promise. We do indeed have the motives and means of censorship in the US comprehensively described – though what is posed as 'potential' seems actually to have been fulfilled – but are left with a question that goes beyond mechanics: why? Why in a country where free expression has more powerful legal protection than anywhere else in the world has this culture of silence taken root? Why, in the absence of the draconian punishments of the gulag or the Lubyanka, are individuals complicit in this silence? We are given all the pieces but no pattern recognition, no matrix in which to assemble the bigger picture.

A look at some of the more recent research on censorship and self-censorship in the US media, particularly but not exclusively in the days immediately following 9/11, could have been instructive. But the media is a strangely absent cultural bedfellow in this survey. Go back, then, to self-censorship. An analysis of the anecdotal evidence gathered in this section could have provided the answer: fear. In the communist world, silence was a small price to pay when fear for one's life and livelihood were an ever present reality. In the US, the consequences of speaking out are of a different order, but it is still fear – fear of offending a patron, a publisher, an owner, an advertiser, the prevailing mood of the nation and, above all, the cultural, ethnic or religious 'other' – that animates self-censorship and the culture of silence on which it depends.

Over a decade ago, in the course of delineating the new, post-Soviet geography of censorship, the US jurist Ronald Dworkin observed that the right to free expression was being challenged by "new enemies who claim to speak for justice not tyranny, and who point to other values we respect, including self-determination, equality and freedom from racial hatred and prejudice, as reasons why the right of free speech should now be demoted." It is around such ironies and ambiguities, compounded by the fear and confusion associated with them, that the US culture of censorship is taking root. But this is the matrix with which Censoring Culture does not engage.