328 Animal Life and Intelligence. 



linked or woven. And the mental process by which we 

 pass from any perceived event or existence to other pre- 

 ceding, concomitant, or subsequent events or existences 

 linked or woven with it in the chain or web of phenomena, 

 we call inference.* When, for example, I find a footprint 

 in the sand, I infer that a man has passed that way ; and 

 when the clouds are heaped up heavy and black, I infer 

 that a storm is about to burst upon us. 



Concerning inference, of which I shall have more to 

 say in the next chapter, I have now to note that it is of 

 two kinds : first, perceptual inference, or inference from 

 direct experience ; secondly, conceptual inference, or infer- 

 ence based on experience, but reached through the exercise 

 of the reasoning faculties. The latter involves the process 

 of analysis or isolation ; the former does not. There is a 

 marked difference between the two. Perceptual inferences 

 are the outcome of practical experience, but do not go 

 beyond such practical experience. Conceptual inferences 

 are also based on experience, but they predict occurrences 

 never before experienced. Perceptual inferences, again, 

 deal with matters practically; but conceptual thought 

 explains them. 



The expectation of a storm when the thunder-clouds are 

 heavy is a case of perceptual inference. It is the outcome 

 of a long-established association, and is not reached by a 

 process of reasoning involving an analysis of the pheno- 

 mena. But if, though the sky is clear, a west wind and 

 a rapidly falling barometer lead me to predict rain, the 

 inference is conceptual, and gained by me or for me by a 

 process of reasoning ; for the barometer was the outcome 

 of the analysis of phenomena. In the mind of the rough 

 sailor-lad, however, the fall of the mercury and the suc- 

 ceeding storm may be connected by mere perceptual 



* We do not speak of the filling in the complement of a percept (the con- 

 struction of the object at the bidding of a simple impression) as a matter of 

 conscious inference. I do not consciously infer that yonder moss-rose is 

 scented. Scent is an integral part of the construct. From the appearance of 

 the rose, I may, however, infer that a rose-chafer has disturbed its petals. 

 The complement of the percept, if inferred at all, is unconsciously inferred. 



