BOSTON (CBS) – It happened yesterday afternoon, a single tweet on a new Twitter account bearing the name of a prominent British news organization reporting that former British Prime Minister Margaret Thatcher had passed away.

Listen to Jon’s commentary:

It was plausible news, since Mrs. Thatcher is 86 and has been very ill in recent years. And so thousands of people – including some prominent journalists – quickly retweeted the story, prompting others to rush online to express their sympathies.

One problem – the story was false, a hoax reportedly perpetrated by a British radio personality.

But the issue isn’t so much the creep who posted it. It’s that it is yet another case study of Internet poison, and how dicey the freedom and speed the web offers can be.

This is not the first time we’ve seen a fake death report on Twitter gain instant traction and circle the globe, so the fact that journalists and others who should know better were so eager to pass it along without any verification is scary.

But the fact is, passing along rumor and falsehood as if it were gospel truth has become an everyday occurrence thanks to the Internet and our own carelessness.

I spent most of my time during the last presidential race debunking online garbage, and this time around the situation is exponentially worse.

Too many political partisans are willing to say anything, no matter how distorted or outright false, and spread their swill as far as they can.

They may think they’re just playing a game, but gullible web surfers are swallowing it way too readily and passing it along to others.

This is already damaging our political and journalistic culture, and seems likely to create even more damage the farther out of control it gets.

So to those of you who still care about truth, or even something close to it, I offer this dispiriting advice – don’t immediately believe anything you see on the blogs, on Twitter, or in your e-mail inbox.

Suspend disbelief, and next thing you know you’re passing the poison onto someone else.

You can listen to Keller At Large on WBZ News Radio every weekday at 7:55 a.m. and 12:25 p.m. You can also watch Jon on WBZ-TV News.