The first generation of the World Wide Web was largely about throwing silly ideas against the wall and seeing what stuck (or at least what attracted enough venture capital to keep Web entrepreneurs in Herman Miller chairs and chai lattes).

But today’s Web 2.0 is all about user-generated content. On the most successful sites, it’s the readers who create the comments, links, and videos that then attract more readers.

Web 2.0 types love to talk about “the wisdom of crowds” — the idea that people make smarter, more accurate decisions collectively than they do as individuals. In other words, the more people who contribute to something, the better it gets.

The classic example of this concept is Wikipedia, the online encyclopedia created and maintained almost entirely by volunteers — no expertise required. But the Wiki also serves as an illustration of what can go wrong with this theory.

Separating what’s true from the noise and disinformation is becoming harder than ever.

Dan Tynan writes this column every month for US Airways Magazine.

On Wikipedia, anyone can create a new entry or edit an existing one. Then the crowd moves in to correct your mistakes. As the entry changes, you can look back and see every version of it that ever existed, as well as who made each edit. If needed, a group of “super Wikipedians’” will weigh in to settle disputes and delete entries deemed unworthy.

In some ways, the system works beautifully. Since the site was launched seven years ago, Wikipedia’s 75,000-plus volunteers have churned out more than 8 million articles in 253 languages. It’s the first destination for millions of Web surfers when researching a topic.

But hopefully it’s not their last, because Wikipedia entries are notoriously unreliable. An entry on the island of Tortuga may be based on “facts” from Pirates of the Caribbean. The section on René Descartes may contain quotes from Scott Adams’s Dilbert Blog. And people censor Wikipedia articles about themselves or the organizations they belong to. To the untrained eye, the entries look like the real deal.

Wikipedians say the encyclopedia ultimately corrects itself, and that might be true. But how long does it take, and what happens meanwhile? As an experiment, I once added a harmless fictional “fact” to the Wikipedia biography of a notable technology executive. Three months and nearly 200 edits later, the bogus sentence was removed. (However, you can still find it on some sites that use Wikipedia as a source).

This is why some original Wikipedians left to start their own encyclopedias and are trying to add more supervision to the process. At veropedia.com, a band of longtime Wikipedia contributors take Wiki articles, verify facts, rewrite as needed, and then present them in pristine “Verofied” form. Citizendium.org, started by Wikipedia cofounder Larry Sanger, lets anyone create articles, which are then vetted by experts. Contributors must create an account; those who post deliberately false entries can be banned. Both sites had produced roughly 4,000 articles apiece at press time — a fraction of what’s available on Wikipedia. Given the vetting process, neither source will likely ever catch up.

They’re not the only Wiki alternatives. The Conservapedia aims to correct what it perceives as Wikipedia’s “liberal bias,” with predictable results. The CreationWiki presents life’s origins through a biblical prism. The RationalWiki offers a science-based response to the aforementioned. Soon we’ll be able to choose the reality we want to believe in, complete with a “fact”-filled encyclopedia to back up our beliefs. Separating what’s true from the noise and disinformation will be harder than ever.

Unfortunately, the flip side of “wisdom of crowds” is mob mentality. And mobs tend to have their own agendas; the truth is rarely a priority.

I’m paraphrasing Descartes. Or maybe Dilbert. Guess I’ll have to go look it up.