bnevin@CCH.BBN.COM.UUCP (03/03/87)
We humans do not usually backtrack over a line of reasoning that led to a conclusion. Instead, we reconstruct what such a line of reasoning might plausibly be. It's called rationalization. How wonderful it is to be rational beings, for we can make plausible whatever conclusions we cherish. --Ben Franklin (paraphrase from memory) As the ordinary usage of the term suggests, rationalization can and often does lead us astray, but that is a critique of the quality of the particular line of reasoning that an individual might reconstruct to rationalize or `make rational' a given conclusion. We reach conclusions by means that are not guaranteed. We need valid rationalization to check them out. Pearce made the point that mathematical reasoning is a tidy pyramidal structure erected after the fact, and that it is better both for presentation and for pedagogy to show the path actually followed, even though it appears less elegant. Few have done this. Does this mean Pearce would advocate expert systems explaining by retracing? I think not, because he explicitly recognized the importance of intuitive hunches in mathematical and logical work. The proof is merely to validate conclusions reached by a less respectable path--to rationalize them. Since our expert systems cannot emulate hunches, a useful approach is to check out conclusions human users have a hunch about. Can they validly be rationalized? Isn't this in fact the use to which many users prefer to put expert systems like Palladian's financial consultant? What is an expert? Some say: an expert is someone who knows a great deal about his subject. I prefer: an expert is someone who knows some of the worst mistakes that can be made in his subject, and how to avoid them. --Werner Heisenberg Bruce Nevin bn@cch.bbn.com (This is my own personal communication, and in no way expresses or implies anything about the opinions of my employer, its clients, etc.)
bnevin@CCH.BBN.COM (Bruce Nevin) (03/06/87)
The bounds of a field are subject to redefinition. Many established fields of today were interdisciplinary in the past. Thus, `when not to step past them' is a complex matter. Is it possible for users of an expert system to ask for information outside its domain, and for it to answer naively, overstepping its proper bounds? Has anyone worked with this level of meta-expertise? For instance, are there systems that address multiple domains and select the appropriate one (or combination) by deduction from interactions with the user? Bruce Nevin bn@cch.bbn.com (This is my own personal communication, and in no way expresses or implies anything about the opinions of my employer, its clients, etc.)