Some random thoughts on item 3 in Paul Kennedy’s thesis as Cecil describes it (bear in mind I’m saying this without having read Kennedy’s book).
Any advantage Europeans had in intellectual liberty is fairly recent - but that makes sense, because European world domination is recent too. In the Middle Ages, you were a lot better off being Jewish in Muslim Egypt than you were being Jewish anywhere in Christian Europe. But now a Muslim can fearlessly stand on a street corner in London and hand out anti-Christian pamphlets, while Iran slaps Salman Rushdie with a fatwa ordering his murder when he publishes a little blasphemy against Islam.
So how did the West get ahead in the intellectual liberty category? I think the first step was when the church began successfully competing for power with the state in early medieval Europe. The church became a major financial power, it could and did finance campaigns by one king against another. It also could spark revolts against kings by excommunicating them, and churchmen became major feudal landholders. I’m not that familiar with Asian history, but I don’t know of any case where Buddhist, Hindu or Muslim clergymen held that kind of king-rivaling power. And in Islam, there was no competition between church and state, because they were the same: the caliph was the supreme religious leader and the supreme secular leader rolled into one.
Obviously, this first step alone wasn’t enough to give the West an edge in intellectual liberty (see above about tolerating Judaism in Egypt vs. Europe). But it did lay the groundwork by establishing a rival to the king’s (the state’s) authority.
The second step was the Protestant Reformation. This established a majority and a minority religious sect in just about every kingdom in Europe. When there was only one church in each kingdom, that church was just as enthusiastic about repressing free thought as the king was. But after the Reformation, whichever faction was in the minority (usually the Protestants) knew it couldn’t enforce religious/intellectual uniformity on the majority, however much they would have liked to. The Calvinists and Lutherans didn’t WANT to tolerate other religious opinions; they HAD to, in kingdoms where they were in the minority, and so their followers pleaded for intellectual liberty as a survival tactic. The Catholics were eventually forced to do the same thing in majority-Protestant countries like England, Scotland, and the Netherlands. The Christian church had already been established as a rival to the state; now for the first time it became in part (never in full) a reluctant force for intellectual liberty.
After getting its jump-start from the Reformation, intellectual liberty became self-promoting, like a positive genetic adaptation in evolution. If you had it, you prospered and multiplied; if you didn’t, you suffered and dwindled. Kings who tried to suppress minority religious factions lost important sources of skill and revenue. E.g., in Spain Isabella and Ferdinand kicked out the Jews and Muslims, depriving themselves of their kingdoms’ juiciest fonts of tax money; the Dutch and Algerians absorbed these people and benefited. For the same reason, the persecution of the Huguenots worked directly to the benefit of England and Swtizerland. Suppression of intellectual/religious liberty also had a nasty tendency of provoking devastating civil wars, as France and the Empire both found out.
Recognizing that the above is a simplification of an irreducibly complex story, my recipe for intellectual liberty is: take about thirty weak States. Throw in pan with one strong Church. Boil for 1,000 years. Break Church into small pieces. Stir well.