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From: yerazuws@rpics.UUCP
Newsgroups: comp.ai
Subject: Re: dear abby....
Message-ID: <886@rpics.RPI.EDU>
Date: Sun, 1-Mar-87 22:06:55 EST
Article-I.D.: rpics.886
Posted: Sun Mar  1 22:06:55 1987
Date-Received: Tue, 3-Mar-87 00:18:11 EST
References: <178@arcsun.UUCP>
Lines: 32
Keywords: justification in expert systems
Summary: Justification makes {acceptance, debug} easier

In article <178@arcsun.UUCP>, roy@arcsun.UUCP (Roy Masrani) writes:
> 
> Dear Abby.  My friends are shunning me because i think that to call
> a program an "expert system" it must be able to explain its decisions.
> "The system must be able to show its line of reasoning", I cry.  They
> say "Forget it, Roy... an expert system need only make decisions that
> equal human experts.  An explanation facility is optional".  Who's
> right?

While you're developing an expert system, you have to know not just 
that it inferred something incorrectly, but WHY it inferred it incorrectly.
Looking through 4,000 rules trying to find the one with a typo is 
no fun, no fun at all.
	
Secondly, once you and your expert have convinced yourself that the 
system is right, you must now convince your first set of users that the
system is right, too.  These users may not be as expert as *your* expert,
but they have some knowledge of the subject.  Perhaps a few of them are even
more expert than your expert in some narrow subfield.  
	
It behooves you to gain acceptance and knowledge from this group, and 
if they perceive that the expert system is a "black box", they will have
no encouragement to assist in the final tweaking and debugging.  To be 
useful, your system must not only be correct.  It must be accepted and
used!  
	
Personal experience- People, including the expert whose knowledge has been
captured, don't like (maybe don't trust?) a black-box expert system, if
they can't ask it why it gave the answer it did.  
	
	-Bill  Yerazunis
	"...these guys had "Thugs 'R' Us" stencilled all over them"