dave: You have posed a really BIG question. philosophers over the years have been all over the place on this one. there are, of course, Aquinas’s famous five ways (including the one you mentioned). there is also anselm’s ontological argument (which aquinas thought was unconvincing). and then there were people like hume and kant who attacked all the traditional arguments, kant finally coming up with a “proof” based on our moral sense.then there are those who use the fact of evil as “proof” that there is no God (or, if there is, that he is a worthless God). my own view is that anything as complex and fine tuned as our universe, had to be created by a superior power, it didn’t and couldn’t have happened by chance. in this regard, you might want to look at some of the recent arguments for intelligent design, including discussions of the so-call anthropic coincidences. but, i must caution, this is just a quick response (and it probably doesn’t fully answer your query). but at least i hope it helps. tom st. martin