AI, NN, and CNS

[Jim Bower]

	Concerning the AI and connectionism debate.  I think that this debate
should take place without reference to biology.  While AI by conviction has
had very little to do with the structure of the nervous system, it is not at
all clear that connectionism is much different.  Even the "neural nets"
subfield, if that is what it is, is at best vaguely connected to real biology.
In my view, the modern interest in either connectionism or neural nets
was not even particularly biologically inspired.  As a biologist it seems to
me that both have emerged from their own antecedents.  Beyond origins,
however, all one has to do is attend any of the annual neural net meetings
to see that biology is currently at best a handmaiden to the overall effort. 
At worst, it is used as a justification for preconceived notions.  This is
not to say that there are not some people in the field who are committed
to understanding what little is now known about biology, but they are few
and far between.  Instead, the evolution of neural networks and connectionism 
appears to be taking their own directions under their own priorities 
with real biological constraints having little effect on either.  
 	More globally, it has been pointed out before that historical attempts
to understand human intelligence have always been cast in terms of the
most sophisticated technology of the day.  The Greeks borrowed from the
technology of aqueducts in ascribing mental processes to the flow of
bodily fluids.  Descartes thought he thought using machines and mechanical 
forces.  Sherrington was inspired by telephone switchboards, while
theorists of the 60's and 70's considered the brain to be a digital computer. 
Today we would discount each of these claims believing that the brain
is a parallel distributed processing device.  It is important to realize,
however, that these earlier speculators did not think the mechanism of
mental function was similar to their favorite machine, they, like we,
thought it was actually just a more complicated version of that machine.  
 	In conclusion, in my view, AI and connectionism (neural nets) should
work out their own definitions on their own merits without reference to
biology.  Then, if there is a difference, both should fight it out based on
real world performance.  At that point, some biologist will probably compare 
the results to the abilities of some invertebrate somewhere making
it clear, yet again, that we have missed the mark.  

Jim Bower
jbower at smaug.cns.caltech.edu