You've asked possibly THE most-debated question in the field of world history right now. It sounds like you've already read a good world history book or taken a course, since the question is well-phrased, but if you haven't, that's where I'd start. Then read Jonathan Daly, Historians Debate the Rise of the West, 2014. The sad thing is that Daly does a great job and it's already out of date - yes, in six years! - because so many have their opinion about the causes. Daly also misses a lot of economic history, which is done in economics departments, not history departments. Once you read his book, try - just try - to read everything he reviews. It's impossible.

Notice that I haven't actually answered your question. That's because there are so many different answers! And each author has his or her own theory, which does not agree with any other theory.

Good luck.