Editor's Note: This is an excerpt from David Ignatius's full February 14th column in the Washington Post.

A death threat arrived last week in the e-mail of James Njoroge Wachai, a Kenyan journalist who has written about the tribal conflict there for PostGlobal, a Web discussion I host with Newsweek's Fareed Zakaria. The authors of the threatening note claimed they were part of the "gang of odm," meaning that they were supporters of the opposition Orange Democratic Movement (ODM) that is challenging President Mwai Kibaki.

"You are writing bad articles about ODM in American newspapers," the note said. "We are watching you and you are a marked man. . . . You will die like a cow."

Wachai exemplifies the kind of open global discussion we sought when we created PostGlobal two years ago. His first post for us, "Don't Balkanize Kenya," denounced politicians in his country who were exploiting tribal divisions to settle political scores. A second post, "Peacemakers Unfit for Peace," chided African leaders who were offering Kenya advice while ignoring human rights abuses in their own back yards. He just proposed a new piece asking why the State Department is so wary of using the phrase "ethnic cleansing" to describe the slaughter in Kenya.

Good journalism is about people writing the truth as they see it. James Wachai is our colleague in that effort. When someone threatens him, they threaten our common endeavor.

When Fareed Zakaria and I created PostGlobal in June 2006, one of the first people we asked to join our panel of global commentators was an Iranian blogger named Hossein Derakhshan. He was a natural choice--smart, outspoken, unpredictable, fearless. He already had a wide following among young Iranians, inside and outside Iran, and we wanted to share his views with a wider audience.

Derakhshan has been a lively member of the PostGlobal group -- sometimes defending the Iranian regime, sometimes criticizing it. Anyone who wants to see the range of his views can go to his page on PostGlobal for a sample of his posts. He returned to Tehran a few weeks ago, after living mostly in Canada since 2000, and we were looking forward to seeing what this iconoclastic voice would say about his native country.

Last weekend we learned that Derakhshan has been arrested and accused of spying for Israel. He had traveled there in 2007, openly and publicly -- writing about his experiences for his own weblog, "Editor: Myself." We fear that his real crime in the eyes of the Iranian authorities was that he dared to visit the Jewish state and write about its people as human beings -- as opposed to the demons of Iranian official propaganda. He was traveling on a Canadian passport, which unlike that of Iran doesn't forbid contact with Israel.

This arrest will only deepen Iran's isolation from the rest of the world. We live on a planet where people are increasingly free to travel, think, talk, and communicate via the Internet. It's a global community in which millions of young Iranians feel part -- we know that from the tens of thousands of Iranian blogs, and from the Iranian traffic we get at PostGlobal. Does the Iranian government really think that it can dam this tide of free-flowing information? Does it imagine that by arresting one of its most prominent young bloggers, it will create anything other than scorn, at home and abroad?

Hossein Derakhshan is part of the international network of thinkers and commentators that is symbolized by PostGlobal. We know that members of this network -- commentators and readers alike -- join us in protesting Derakhshan's arrest and calling for his freedom.