Worldview Manager is a prototype for a framework and website that help users uncover hidden inconsistencies in their personal beliefs ("worldviews").
The website does not actually understand the belief systems nor consider one to be more correct than the other. Instead, it has a record of which opinions are logically inconsistent; the user selects some "topic" and the website presents him or her with a series of statements in that topic, one by one -- the user indicates agreement or disagreement with the statement, and the system detects when some response contradicts previous responses.
Worldview Manager is written from scratch, primarily in PHP, but with some components in Haskell and Scheme. It is generously hosted by the Massachusetts Institute of Technology Computer Science and Artificial Intelligence Laboratory. The contents, design, and source code of the website are all available under the Apache Software License Version 2.0. The source code may be viewed and downloaded at http://www.gitorious.org/worldview.
For the interested, there is also a very comprehensive manual about the inner workings of Worldview Manager.