Is AI (artificial intelligence) science or not?

AI is science, isn't it?
I think it is. We discussed it on 501 class tonight, one of my classmate thought that machine learning is a kind of AI, but it mainly deals with math problems, so it is not science. But I thought his understanding of machine learning is not accurate, bacause the fundamental rule of machine learning is pattern recognition, and the basic rules of pattern recognition is Bayesian Decision Theories. And these theories are based on how human make decision. So it is science.

After this discussion, one of my other classmate asked us an other very good question:" Why do we need to discuss that AI is science or not?"