If the internet is, as it's often called, the Wild West, then the comments sections of popular blogs are its Deadwood: a lawless no-man's-land of profanity, brawling and every variety of ignorance and crassness.

Two recent events have made this situation clearer than ever—and, in the process, raised questions about whether the people who own and write blogs can or should be held responsible for the excesses of their readers.

On the Huffington Post, discussion took a nasty turn last month after it was reported that Nancy Reagan had been hospitalized after a fall. Although the site's policy specifically prohibits comments that "celebrate the death or illness of any person," some commenters did exactly that, thus attracting the wrath of Fox News host Bill O'Reilly, who compared Arianna Huffington to a Nazi for her role in enabling such vileness.

(The irony of resorting to overheated, spiteful invective in order to decry the use of overheated, spiteful invective apparently escaped O'Reilly.)

Meanwhile, in Chicago, 40-year-old advertising executive Paul Tilley jumped to his death from a hotel room. Press accounts linked his suicide, albeit tenuously, to critical posts and anonymous comments about him on ad-industry blogs. (Tilley's friends dismissed any such connection.)

Advertising Age columnist Bob Garfield, like O'Reilly, brought in the Nazi comparison, seeing an echo of Hannah Arendt's phrase, "banality of evil," in the cruelty of blog pile-ons.

"What passes online for opinion, analysis, criticism, and commentary too often lacks logic, coherent argument, evidence, intellectual rigor, or even simple honesty," Garfield wrote. "It wallows instead in snide cheap shots and ad hominem bile, scurrilousness and schadenfreude, free-floating hostility, and bullying disguised as wit."