Multiculturalism, cultural diversity, cultural pluralism: in the United States few causes have won such widespread enthusiasm. These phrases kick off a thousand speeches and articles; they appear in hundreds of essays and books. Government officials, college administrators, corporate executives, museum curators, high-school principals—to name just a few—declare their commitment to multiculturalism. One sign of the times: the American Council of Education published a guide to programmes and publications on cultural diversity that runs to four hundred pages.

Even conservatives, who might be expected to resist a liberal steamroller, often join in, confining their objections to fringe formations, not the thing itself. Publicly at least, they hesitate to protest a larger multiculturalism. To establish its credentials, a conservative foundation puts out a magazine called Diversity edited by an African-American with a Jewish name, David S. Bernstein.

These causes were not always so popular. Horace M. Kallen, who virtually copyrighted the term ‘cultural pluralism’, stated in 1924 that the idea was ‘popular nowhere in the United States’. He knew why. Vast immigration and the First World War aggravated fears of foreigners; Americanization and assimilation, not pluralism and diversity, became the watchwords. For Kallen the revived Ku Klux Klan exemplified a repressive American conformity: ‘The alternative before Americans is Kultur Klux Klan or Cultural Pluralism.’

Seventy years later everyone has joined Kallen in celebrating ‘cultural pluralism’. Why? Is this a case of victorious liberalism? Has a dissenting programme supported by Kallen and a few other intellectuals won over everyone? Has a new and varied immigration forced recognition of cultural diversity? Have Americans become more tolerant, liberal and cosmopolitan? Perhaps, but this is hardly the whole story—and perhaps none of it.

Let me put my cards on the table: multiculturalism and the kindred terms of cultural diversity and cultural pluralism are a new cant. Incessantly invoked, they signify anything and everything. This is not simply an example of sloppy terms; these phrases have become a new ideology. To put it provocatively: multiculturalism flourishes as a programme while it weakens as a reality. The drumbeat of cultural diversity covers an unwelcome truth: cultural differences are diminishing, not increasing. For better or worse only one culture thrives in the United States, the culture of business, work and consuming.