SENSATION AND PERCEPTION 125 



44. ON THE MIND AND ITS OPERATORS 



From the naively biological standpoint it is convenient to 

 postulate a mental mechanism or mind. The mechanism is not 

 cerebral in the strict sense — that is, it is not what is implied in 

 receptors, peripheral and central nervous systems and effectors. 

 I'he mind is not a tabula rasa on which experience writes, neither 

 is it something which has ideas before it has experience. It is 

 a mechanism in that it does not operate " anyhow " but in an 

 orderly and typical way. It exhibits type in that it is *' the 

 same " in groups of animals that can be arranged into morpho- 

 logical categories. It is " the same " in all the animals of the same 

 categories (say dogs, horses and men) within the limits imposed 

 by fluctuations, mutations and secular evolution. It is evolved 

 and is not invariable in the strict sense and mental operators 

 may be individually developed by trial and error, or they may 

 be " acquired " (see Section 87). 



We can best discuss the mind as a bundle of *' operators " 

 which we can arbitrarily isolate by introspection and consider, by 

 analogy, in other animals than ourselves. But actually the 

 operators integrate so that the mind is a unity. The operators 

 deal with the raw materials of sensation after these have been 

 intuited and inserted in the frameworks of duration and space. 

 The operators we may divide into the elementary ones of quantity, 

 quality, relation and modality — these are the famous Kantian 

 " categories of the understanding " and no scheme seems better 

 to assist in biological investigation. But human evolution has 

 given us secondary, or acquired categories, or operators, and 

 these we shall also consider. 



44«. The Elementary Operators. 



/. Quantity. The mind has in it, with respect to the sensory 

 data received, the consciousnesses of one thing, or many things, 

 or of the degrees of manyness, or number. A pack of cards is 

 perceived as one thing, but it is decomposable into many things 

 — a unity of 13 spades, 13 clubs, etc., or 52 different things. 



a. Quality. The things are different in respect of their 

 quantity, 52 cards or 13 spades, 13 clubs, etc. But they are 

 perceived as not alike in quality, a spade being different from 

 another spade just because there is one spade and another spade. 



