COMPARING THE BRAIN WITH MACHINES — MacKAY 237 



leading to numerical predictions. This satisfaction we must cheer- 

 fully leave to folk with a different type of problem. 



But behind this approach to the study of the brain there lies a more 

 general motive. It is the hope of providing a working link between 

 the concepts of psj^chiatry and those of physiology and anatomy. Co- 

 operation at present between those fields is hampered by the sheer 

 difficulty of imagining physiological correlates of some psychiatric 

 terms and vice versa. 



Now the language of information and control lies, in a sense, be- 

 tween the languages of psychiatry and physiology. In the informa- 

 tion-flow diagram of a successful model we may hope to find features 

 representing concepts from each language. Some of the data of 

 psychopathology even now can be translated into terms of informa- 

 tion flow, so as to suggest testable physical hypotheses.* 



I need hardly say that this is rather different from naively assimilat- 

 ing mental disorder to the ills of digital computers, a pastime which 

 has justifiably irritated those more painfully close to the problem. 



To summarize, the considerable effort going into this theoretical 

 modelmaking is justified chiefly by the hope that out of it may come 

 a way of describing the thinking process, sufficiently close to psychi- 

 atric realties to be useful in diagnosis, yet sufficiently operational and 

 objective to allow the physiologist to make his maximum contribution 

 to the study and treatment of mental illness. 



You might call it conceptual bridge building — an activity set about 

 with pitfalls and attractive to cranks, but withal one of the most 

 promising ways of enlarging our understanding of what happens 

 when we understand. 



POSTSCRIPT ON PERSPECTIVE 



May I conclude with a word of warning. This kind of inquiry is 

 often misconceived — and sometimes attacked — as an attempt to "de- 

 bunk man." "If my actions were nothing but the end-product of a 

 chain of physical causes, where would things like my decision come 

 in?" is a typical question. It may of course be true that people who 

 do wish to "debunk man" imagine that a complete physical explana- 

 tion of his brain would be grist to their mill. But if so I believe that 

 they err in company with their opponents who base their arguments 

 on the same premise. The villain of the piece here is usually the 

 phrase "nothing but" — the hallmark of what we may call reductionist 

 thinking. 



If I say that an electric advertising sign is "nothing but" a certain 

 array of lamps and wires, I may mean one of two things: (1) I may 



* I have in mind, for example, those hallucinations that suggest diversion rather 

 than absence of signals to correct the internal matching response. 



