I'm married to a biology PhD, and at one point spent a couple of years watching people, including biologists, deal with a constant stream of Creationists in places like talk.origins.<p>My experience is that if you're a personal friend, you get more serious conversation.  If you're someone they know but not so closely, they'll have the argument if pushed but don't feel the need to actively educate.  And if you're a random person spouting on the Internet, it isn't worth their time to get involved.  If pushed to be involved, they don't feel the need to be pleasant about it.<p>After spending time myself explaining the same thing over and over again, I've come to feel the same way.  I've also come to realize that there are plenty of smart people who do not wish to be educated.  Including in my direct personal experience, at least one PhD in mathematics and another in molecular biology.<p>Based on this experience I have some sympathy for the position of climate scientists.  You spend your life climbing around glaciers in Greenland, and you don't really feel like spending the rest of it convincing people who don't want to bother learning the basics about climate.