Byron M. Roth, Professor Emeritus of Psychology at Dowling College and author of The Perils of Diversity: Immigration and Human Nature, on the link between multiculturalism and political correctness:
"Not surprisingly, the multicultural program these elites promote is, by its very nature, profoundly undemocratic, in that it imposes changes on society that citizens most assuredly do not want and which they resist when given the opportunity to do so. Hence the extraordinary repression of dissent in the immigration debate and the totalitarian imposition of political correctness wherever elites have power."
According to Roth, state-sanctioned multiculturalism can only be maintained through coercion:
"From the perspective of inclusive fitness, unfamiliar others are potential free-riders and, out of a concern that they will be exploited by others, people reduce considerably their altruistic attitudes and behavior in a general way in more diverse communities. This loss of trust is a symptom of a breakdown in social cohesion and is surely a forerunner of the sort of ethnic conflict that is always likely to break out if allowed to do so. This is undoubtedly the reason why multicultural nation-states are forever promoting tolerance and ever more punitive sanctions for the expression of ethnic hostility, even going so far to as to discourage the expression of opinion about the reality of ethnic and racial differences. Currently these measures are directed at the host population when they express reservations about the wisdom of mass immigration, but this will surely change as it becomes ever more obvious that it is the presence of competing ethnic groups that is creating the tension and not the expressed reservations of the majority population. The real danger for modern democracies is that in their zeal to promote multicultural societies, they will be forced to resort to the means that have characterized all empires attempting to maintain their hegemony over disparate peoples."
You can purchase Roth's The Perils of Diversity at Amazon.com.