h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Although this is an interesting entry, it is not very informative unless you already know a lot about ai.
for a long time, ai has been regarded as that part of computer science that deals with making computers do stuff, that if done by a human would be a sign of intelligence. It is the part of computing to do with getting them to do things that we don't know how to do very well.
It is then subdivided into social ai, and technical ai. social ai deals with the man-machine interface, and a good example of this is the turing test.
technical ai deals with making clever tools, and is the sort of thing that expert systems and neural nets tend to be about.
You state that you can't know how neural nets work. this is not true, as there has been a lot of success with using fuzzy logic, and nets not in the training mode, along with the training data sets to map the finished logic of the neural net, leaving you with a fuzzy expert system that you can interigate to find out how it works.