I accept as a fact that there has been and continues to be something going on which matches on some levels what we consider to be evolution. I also accept that evolution is a very young science about a very long process and most of our explanations of how it happens are probably wrong, but eventually we'll figure it out. We've gone through the same process with almost every subsection of scientific thought, from our study of gravity to our study of the weather through to our recent advances in aerodynamics and electricity.
It's a vague pronouncement because you can't describe ANY science in under 1000 pages with any but vague pronouncments. Science is prety complicated stuff, and most sciences got a lot more complicated once we started dissecting atoms. What caused evolution to happen is a completely different science, abiogenesis, and until that science has an answer that can enumerate with high confidence exactly what the first life forms were which will then give evolution a starting point to work from they will remain completely seperate sciences. Under the current state of evolutionary though what caused it all to happen is immaterial, could be primoridial ooze, could be the Judeao-Christian God, could be an asteriod, could be aliens, could be Titans, doesn't matter. Evolution is all about figuring what happened to species X which isn't around anymore but there's these other species around that look a lot like it.
But that's - the whole question. That's the sum of the difficulty. What the heck - is it? How do you state it? How do you define it? I don't mean to sound like some bad impression of Fishburn's Morpheus. But c'mon. Science. You know? Definitions. Specifics. Formulas, even?
Science is prety complicated stuff
Revelation is much more so. But Catholics have four principle Creeds, the first three of which are very succinct, and to the point (the fourth's only just a bit longer, and covers more ground). Many statements of scientific theory are similiarly succint, and to the point. There's more to it. Each word or phrase may have a series of books devoted to it. There's FAR MORE to Catholicism beyond the creeds. But there they are. And they exist. And where it this, for evolutionism? Where's that Theory you hear so many talk about?
What caused evolution to happen is a completely different science, abiogenesis
Not what was the first cause for the first creature - but rather do you have any theories to explain this 'fact' of evolution about the speciation and changing species of one, and etc., however it is you define it?