The interesting thing about these Caliphate-revival movements is that the act of calling for a Caliphate follows, in general, in the tradition of jihad ('striving', that is to say, pursuit of a true state of submission to God; work in the name of Islam): it is fundamentally saying, "things are wrong, and this perhaps is our solution."
But the Caliphate is entirely non-Quranic. It's deeply tied to the Sunni/Shi'ite split; the first Caliph was Abu Bakr, a close chum of the Prophet. The schism was that the Shi'a ('party of Ali') wanted the Prophet's (adopted, albeit) grandson, Ali ibn Abu Talib to suceed him, and felt that the Prophet had indicated as such, whereas the Sunni ('people of Muhammad', or somesuch, in that
fine tradition of ambiguous but deeply loaded names) felt succession should follow the Prophet's companions.
So you get to this point of jihad, of that classic spirital questioning, of introspection and possible re-invention: 'we are astray and now what do we do to fix that?' But instead of any of the dramatic reforms that have historically realigned and rejuvinated religions (i.e. the Protestant Reformation, Zen Buddhism, etc), the introspection is relatively short-sighted, the solution is remarkably partisan, and the whole thing just continues.
So the notion is funky:
- It is fundamentally Sunni, in much the way issues within Islam tend to quickly trace back to the Sunni/Shi'a split and the theological/jurisprudent ramifications of who believed what when and what that meant then.
- The Caliphate is not a concept rooted anywhere within the Qur'an or Haditha; it came about after the Prophet died. My emphasis on this point probably betrays my inherently Shi'ite leaning, as my main professor of Islam back in the day had a fairly strong bias himself.
- At its heyday the Caliphate was a remarkably secular institution, with most of religious Islam viewing the ruler as fairly corrupt, etc; there was a very limited period of religious guidance from the Caliphate that then shifted into the gradual transition from Caliphate/Islamic government to Ottoman Turks/ehh. The Caliphate was far from perfect, so why idolize it?
It's hardly my place to say, being neither a scholar of Islam or even a Muslim (I know about enough to get the conjugation of 50-75% of my terms right, and about 25-50% of my concepts right, maybe). But if any reform is to succeed, my impression is that it need be radical and reach deep. When it came about, Islam was radical; it rose out of a deeply hedonistic, relatively anarchic/barbaric tribal sitution that was rife with infanticide, misogyny, raping, pillaging, etc; even on these points where people today say "that part of their Islam is backwards", there is room to argue that taken within its cultural context it was a radical social reform loosely in the direction of more contemporary, western society *, and that the /trend/ set by Mohammad could be continued much further. He used Eucalyptus twigs to clean his teeth; we have toothbrushes.
So I say look at the Arabian penninsula shortly before Mohammad, and shortly after; look at what changes came as a result of Islam, and see where they might lead today. Get the /vector/ of the Prophet; think not 'let's find a good era to go back to' but 'what should the Islam of tomorrow be.'
(*: the exceptiton to this is generally not a tenet of Islam so much as a holdover of the regional culture before Islam; female circumcision, honor killings, etc.)