If you've ever tried to persuade a global warming denier -- and it's frightening to realize there are actually deniers still around in great numbers -- about the reality of human-caused climate change, you know how maddening such conversations can be. The same is true when talking with some people about other aspects of green living -- whether it's vegetarianism or veganism, animal rights, organic agriculture, etc. -- with which they disagree: the discussion can turn unpleasant, even ugly, when your counterpart starts questioning your intelligence, your motives or even your own ethics.
While it's hard to resist fighting fire with fire in these circumstances, try to avoid doing so. The best way to bring around supporters to your cause always requires sugar, not vinegar. So stay calm, stick to the facts (and make sure you have your facts straight first) and fire away at the arguments, not the arguee. If might not work every time -- maybe not even most of the time -- but you'll always gain more respect in someone else's eyes if you demonstrate that you can stay above the fray and retain your cool, even your sense of humor, even when the discussions get heated.