Quran is a protected Book. This protection is done by Allah through majority of Muslim Ummah. If Quran’s protection is done by Allah through principle of majority, it may be inferred that principle of majority is the linchpin around which decision-making in an Islamic state revolves.
“Verily We: It is We Who have sent down the Dhikr (i.e. the Quran) and surely, We will guard it [from corruption]” (al-hijr-9).
From afore-mentioned verse, it is clear that Quran is a protected book, and Allah is protecting it from being corrupted. But the question is how Allah is ensuring protection of Quran; what ways and means Allah adopts to achieve protection of Quran.
Suppose any person changes any verse of Quran and whole Muslim ‘Ummah’ or majority of Muslim ‘Ummah’ accepts such change, it would mean, for all practical purposes, that change has occurred in Quran. This is how change in previously revealed books has occurred; majority of each of previous ‘ummahs’ (both Christians or Jews) followed corrupted form of their respective revealed book; that is why Allah has labeled previously revealed books as corrupted books. It means Allah is protecting Quran through Muslim Ummah’s majority opinion; in other words, Quran is being protected by Allah through application of principle of majority.
From the foregoing discussion, we may infer that, in an Islamic state/society, principle of majority has to be basis of decision- making regarding various issues. But as far as establishment of Islamic sate is concerned, all members of Muslim society (whether in majority or minority) are all the time under obligation to install Islamic state, if they are ruling nation (al-maidah-3; al-imran-85; al-fath-28); but if they are non-ruling nation, they are under obligation to install Islamic state ( whether in majority or minority), when there is opportunity to do so. (for details plz see my article ' Qattal and its imperatives').