Ebonmuse has an excellent short piece on the Disco Dancers’ “teach the controversy” ploy. The money paragraph:
The problem with “teaching all sides” is that it can give fringe ideas a credibility they have not earned. Excessive concern for “balance” leads to presenting the speculations of cranks and crackpots as if they were on equal footing with the positions defended by vast majorities of qualified experts. (The media has a similar problem.) And this is very useful to advocates of pseudoscience, who often do not need to win the rhetorical battle outright; they can triumph merely by muddying the waters and preventing a consensus from forming around the truth. This is the same strategy employed by tobacco companies, as we can see from the second excerpt above, as well as by oil companies seeking to forestall regulation of greenhouse gas emissions.
To Ebonmuse’s list of movements employing the same tactic one can add HIV denial (cf. Phillip E. Johnson and Jonathan Wells).
And Ebonmuse adds a nice touch:
But with all that said, the idea of teaching the controversy isn’t an intrinsically bad one. There are plenty of subjects that have legitimate controversies where this commendable call for fairness could be better applied.
For example, how about sex ed? A great many religious conservatives - many of the same ones who call for teaching the controversy on evolution, I don’t doubt - change their tune when it comes to public-school health classes, demanding that students be taught an “abstinence-only” program that omits contraception, or mentions it only to discuss its failure rates. How strange. Whatever happened to fairness? Whatever happened to learning about all sides? Why can students make up their own minds about evolution, but not about how to protect themselves from STDs?