Online Comments: Freedom of Speech or the Bane of the Internet?

Popular Science wants online comments to encourage learned debate but finds that so many are so wrong they damage the credibility of important research. So they've decided to ban reader comments online. The Huffington Post gets nine million comments a month, but 75% are so vile, mean or obscene they never get posted. We hear why some websites won't allow anonymity any more, while others are banning online comment completely. Does free speech have to be limited to expertise or good manners? Are 100 stupid, cruel or disruptive comments worth one that makes for good reading?