I was dubious about the efficacy of expert systems when we talked about them in class last week. It seemed to me that an expert system would be well suited for simple yes and no problems. Acting more as a reflex agent then something truly intelligent. I didn't see a great difference between having an expert system and having an extensive run book, or an elaborate flow diagram. Even though both of these are very useful, why bother turning them into expert systems, instead of just having them remain as searchable text.
In fact, it seemed like there would be only very special use cases where the cost of developing an expert system would be practical versus the savings it could generate. Expert systems are not simple to build at all, and require a large amount of man hours in setting up and maintaining them. Not to mention that the labor needed for them is very skilled, there is only a select subset of the population capable of programming them. In other words, you need an expert to build expert systems, and experts are expensive.
Another issue would be getting the subject matter experts to cooperate with the programmer. It would not be surprising if some experts do not want a computer to know what they know; job security is an important aspect to some people. What happens for issues where experts disagree on how a situation should be resolved, if it happens once it might not be very problematic, but if it happens continuously one experts knowledge might need to be excluded from the system. Actually getting the knowledge is out of someone's brain is a much bigger issue then we made it seem. This is known as the knowledge acquisition problem, and it actually has deeper roots as a philosophical issue.
I see an expert system as having an inherent lack of flexibility, one mistruth in the knowledge base could pollute all possible solutions. Finding these would take up most of the developers time, again leading to more overhead. Trusting a knowledge base as complete is dangerous as things can change quickly, or Simpsons Paradox could take hold in a knowledge base. There is a strong reliance on the fact that the knowledge bases can be exhaustive. Yet, after studying state spaces for half a semester, one realizes just how large "exhaustive" can mean.
Even with my skepticism expert systems have seen some interest over the last forty years. Perhaps the most intriguing application of the expert system is the multiple attempts for medical diagnosis. There is a compelling reason for experts to want to help build the system, saving lives. And any cost involved in development can be justified due to the fact saving one life outweighs any monetary cost. The question is why didn't they catch on then? I haven't been able to find any argument as to why. It isn't clear if the business reasons were at fault, or if they in fact just didn't work. Maybe the reason was that people are just distrust-worthy of a computer as a doctor.