I ran across a professor's web page years ago-- can't find it now, but he advised that when these topics (global warming, evolution, politics, religion, etc.) come up in conversation, ask this question: "What would it take for me to change your mind?" If the other people in the conversation can't or won't tell you what kind of proof or evidence it would take to change their minds, don't bother.

This advice has saved me untold hours of frustration and bad feelings with friends and family. 8-)

sometimes i get so darned frustrated with load times over the cans-and-strings internet here in KC!