I would just like to recommend that you keep track of where each bit of information comes from. A system that regurgitates knowledge is only as good as its sources, so keep track! This is something that would have to be in place before your project gets too big, so do it as soon as possible.

When presenting the information, how about something like this:

> What is the population of China?

The population of China is [some number]

This knowledge is from:

1. xxx

2. xxx

3. xxx

[click to see the rest]

The ordering could be determined like pagerank, where sources that have more information are ranked higher.