A lot of fluffy nonsense has been spoken about multiculturalism in recent years, partly through ignorance. For many of those who employ the term prefer to use it as a catch-all for feelgood liberal inclusiveness while overlooking what the logic of applied multiculturalism means in practice.
Wikipedia defines multiculturalism as a "de facto state of both cultural and ethnic diversity within the demographics of a particular social space" - merging it with the concept of pluralism tout court.
Yet rather than simply referring to the existence of diverse cultural groups, official multiculturalism policies "aim at preserving the cultures or cultural identities - usually those of immigrant groups - within a unified society. In this context, multiculturalism advocates a society that extends equitable status to distinct cultural and religious groups, no one culture predominating".
Although this seems a straightforward desire for mutual respect at face value, in reality it is anything but. If no one culture predominates then it makes it very difficult to argue for 'one law for all' as the Home Secretary has repeatedly done.
For Britain's Laws (many of them ancient), as Bishop Michael Nazir-Ali has rightly said, derive from Judeo-Christian principles for all the 'secular' spin that is put on them. Thus, in a truly 'multicultural society' they must be considered culturally biased rather than neutral, and thus open to opposition from other communities.
This in turn throws into relief what it means for something to have a universal value. Human Rights, for example, are often claimed to be fundamental and indivisible - acting as the framework around which all legal systems should be constructed.
Yet the concept of Human Rights derives from certain channels of thought which, while not necessarily 100% Western in origin (and here I doff my hat to Amartya Sen's critiques), certainly does not have a universal provenance. Hence one reason that the OIC drew up its own 'Islamic Bil of Human Rights' back in the day.
If we are prepared to admit that multiculturalism entails "equitable status to distinct cultural and religious groups" then our cultural relativism must extend as far as this framework of first principles, if policy making is to be coherent. Which leaves little to nothing that can be deemed suitable for legislation for society at large, based even on the principle of reasonable pluralism.
Of course, there is one further problem with a policy which requires every cultural community to make its own rules - schism and minority viewpoints. Every culture, every organisation, no matter how small, has its renegades, its leaders, and its followers. Thus the question of who makes the rules and who is bound by them is crucial.
Too often, experience across all religions shows that elderly bearded men have the monopoly on this position, giving others little say in writing the rule book. If a completely homogenous group cannot be defined it will be difficult to make legitimate law on all of their behalfs.
Not only is Sharia neither static nor homogenous (as the Archbishop acknowledges) but different schools of fiqh have differing interpretations of what it requires, to which individual Muslims adhere.
Indeed some scholars like Tariq Ramadan believe that even the shariat provisions on which these schools agree cannot be implemented because today's conditions are unlike those of the umma in the time of the prophet - poverty, for example, could be an excuse for stealing while at that time social organisation meant no one was without sufficient food - so the debate is entirely hypothetical.
And then there is the question of dissenters. The Archbishop says that those who decide to pursue justice through Sharia Councils (as in Jewish courts or Somali customary courts) must agree with the punishment meted out or their case will be referred to the Supreme Court.
Yet this is simply one more example of multicultural window dressing which is logically incoherent. If the whole point is respecting the equality of different cultural traditions it is clearly absurd to put British Law on a pedestal.
If the point is giving people choice it could well turn to the advantage of the strong, as it gives plaintiffs the opportunity to pick the version of justice which suits their interests - and pressurise the weak into accepting decisions for cultural reasons, as Earthquake Cove correctly points out in this post.
So we have a choice: either package people as community members and leave it up to their communities to dispense justice - or acknowledge we are all members of one society so we must live under one set of rules which (while open to discussion and debate) must be applied to all, with few exceptions, as is currently the case.
The truth of the matter is that the Archbishop's comments on the place of Sharia in Britain simply reflect what is already happening, since Sharia Councils, like other advisory bodies, seek solutions on non-criminal matters pertaining to their faith which, if disputed, go straight to the high court. That's what he means when he says it is an already accepted part of Britain's legal-political landscape.
What is problematic is not this kind of culturally-sensitive problem solving but the concept of parallel legal systems which is what multiculturalism entails.