8/17 THE IIOMEOSTAT 



8/16. If we grade an ultrastable system's environments accord- 

 ing to the difficulty they present, we shall find that at the ' easy ' 

 end are those that consist of a few variables, independent of each 

 other, and that at the ' difficult ' end are those that contain many 

 variables richly cross-linked to form a complex whole. (The 

 topic is developed from Chapter 11 on.) 



The living organism, too, would classify environments in 

 essentially the same way. Not only does common experience 

 show this, but the construction and use of ' intelligence tests ' 

 has shown in endless ways that the easy problem is the one 

 whose components are few and independent, while the difficult 

 problem is the one with many components that form a complex 

 whole. So when confronted with environments of various ' diffi- 

 culties ', the ultrastable system and the living organism arc likely 

 to fail together. 



8/17. The last few sections have shown, in several ways, how 

 several ' inadequacies ' of the ultrastable system have made us 

 realise, on closer scrutiny, the inadequacies not of the ultrastable 

 system but of the living brain. Clearly we must beware of con- 

 demning a proposed model for not showing a certain property 

 until we are sure that the living organism really shows it. 



Since this book was first published, I have often had put to me 

 some objection of the form ' Surely an ultrastable system could 

 not . . . ' When one goes into the matter, it is surprising how 

 often the reply proves to be ' No, and a human being couldn't do 

 it either ! ' 



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