aarons@syma.sussex.ac.uk (Aaron Sloman) (01/15/91)
valdes@cs.cmu.edu (Raul Valdes-Perez) writes: > In article <4178@syma.sussex.ac.uk> aarons@syma.sussex.ac.uk (Aaron Sloman) writes: > >All the people I talked to in the AI field in the early days were > >very clear that there was a difference between what they were trying > >to implement and how they were implementing it, although it was > >agreed that sometimes making the distinction was not easy (hence the > >occasional confused person who called a program a theory). > > Could Prof. Sloman make clear why computer programs do not merit the status > of theory? Would he accept a system of differential or difference equations > as a theory? This could take us into a long discussion of issues in the philosophy of science, about the nature of theories, models, explanations, etc., which I'd rather not get into and which would not be appropriate for this news group. But I had in mind only the relatively simple point that most AI programs that are intended to model some bit of reality (like many computer models) have a great deal of detail that is there not because it corresponds to anything in the thing being modelled but because (a) it is required in order to get the model going on the particular hardware and software platform (b) it is required for coping with the artificial data simulating the real environment and/or (c) it is required for nice glossy user interfaces for demonstrating the software etc etc. When this happens it is all too easy for people (including me) to be unclear about the distinction between those aspects of the program that are essential to the theory that is being demonstrated and those that aren't. E.g. think of an AI vision program intended to model some aspect of human vision, that takes input in the form of a regular rectangular array: much of the code will be geared to the structure of that array. Will all the edge-detecting algorithms that work on the array be part of the theory of how animal visual systems work, or will it be an implementation detail providing input to some other part of the system that is intended as the real model? If the input to that other part has an "unrealistic: form because of how it is derived, does that mean that only certain aspects of the intermediate mechanisms are intended as part of the theory? Which aspects? It isn't always easy to be clear about this. Unfortunately no interesting AI theory about the workings of the human mind or brain can be expressed in a few simple equations. This is closely related to the critique David Marr made of some of the work in AI in the early 70s, though I think his alternative approach stressed the study of the nature of abstract problems at the expense of workable solutions able to cope with real-time constraints, poor data, malfunctioning sensors, etc. (But lets not get into that now!) Aaron Sloman, School of Cognitive and Computing Sciences, Univ of Sussex, Brighton, BN1 9QH, England EMAIL aarons@cogs.sussex.ac.uk