An Oxymoron?

Is the term "political science" an oxymoron? While I understand that the actual process of the formation of a new law can be studied scientifically, doesn't the agenda of individuals or groups remove the scientific aspect from the process? Let's take gay marriage as an example. Can we scientifically come to a solution that will result in a law either approving of it or banning it? I don't think that we can. The Constitution is open to individual interpretation and depending on your background, it will color your view. I think that "politics" and "science" are mutually exclusive terms. Discuss.