One of the things the old expert systems like MYCIN could do was answer the question "Why", as in, why did you come to that conclusion? And it would show its reasoning. I may be mistaken but I don't think that the new, neural net based systems can do that. Interesting regression if true.
That was a problem in the early days. Expert systems could support root-cause analysis or justify themselves whereas neural nets couldn't. The new things are close to neural nets in operation. I'm doubting they can do it by default given that. Be interesting to see if anything is developed along those lines given work such as visualization of various layers of deep learning in pattern recognition.
