This is a cautionary tale about how journalism sometimes gets practiced in contemporary America.

A few weeks ago, a reporter for The Wall Street Journal named Amy Chozick got a bright idea for a news story: In a nation where, according to our public health authorities, nearly two-thirds of the adult population is too fat, is Barack Obama too skinny to be elected president?

Now you may think that sounds like a very unpromising hypothesis upon which to construct a piece of investigative journalism. After all, the idea that a svelte as opposed to a fat build might be a disadvantage for a presidential candidate seems wildly implausible given that we live in a culture that celebrates thinness and despises fatness.

On the other hand, have you ever worked for one of America's major newspapers? Read on and learn how through the magic of the Internet it's now possible to "report news" you in fact largely invented yourself, thereby creating a national and indeed international news story out of very thin air.

I emphasize that Chozick wasn't writing an off-the-wall opinion piece in the style of, say, the increasingly off-the-wall Maureen Dowd (about whom I'll say more in a minute). Instead, she was supposedly doing investigative journalism, which requires, at a minimum, some investigation.

Here's the method she employed to determine whether Obama's skinny physique might be a problem for him in the presidential race. She posted the following message on a Yahoo Internet message board: "Does anyone out there think Barack Obama is too thin to be president? Anyone having a hard time relating to him and his 'no excess body fat'? Please let me know. Thanks!"

And here are the results she gleaned from this intrepid bit of journalism: a total of one purportedly substantive response from what Chozick characterizes as a Clinton supporter but which reads like someone yanking Chozick's chain. Nevertheless, Chozick quoted this source - somebody going by the name "onlinebeerbellygirl" - to confirm the thesis of her story: "I won't vote for any beanpole guy."

Keep in mind that this quote was solicited by Chozick herself from an unmoderated Internet message board - something she failed to reveal to her readers. If I got it into my head to write a story about how some Americans might be hesitant to vote for Obama because they suspect he's really a space alien from somewhere in the Oort Cloud, I guarantee I could elicit a whole bunch of anonymous quotes on the Internet to confirm my hypothesis.

This wasn't the only faux pas in Chozick's story. She also included, without attribution, a passage that closely paraphrased a McCain campaign news release criticizing Obama's nutritional and exercise habits, and she made the egregious mistake of claiming that there hasn't been an "overweight" president since William Howard Taft. In fact, according to the definitions used by our public health authorities, most U.S. presidents over the past century have been "overweight," including the present occupant of the office.

Yet within 24 hours this absurd exercise in creating news for the purposes of reporting it had taken on a life of its own. National and international media repeated Chozick's findings. The Times of London ran a feature on how some American voters were supposedly concerned about Obama's weight, citing (naturally) Chozick's piece as evidence.

The following day, in The New York Times, Maureen Dowd used Chozick's reporting as a basis for a column on why some Hillary Clinton supporters were purportedly failing to warm up to Obama's candidacy.

Thus does our contemporary media echo chamber operate, mistaking its own weird little obsessions for the actual concerns of the audience it's supposed to be edifying.

Paul Campos is a professor of law at the University of Colorado. He can be reached at paul.campos@colorado.edu.