8 COMMON SENSE (aND SCIENCE) 



fully pictures what is given in its full complexity, but rather a realistic 

 theory arising from the realistic conviction that "only sensations can 

 really be given." Nevertheless, one may believe in a subconscious 

 weaving of the whole pattern out of such elements called pure sensa- 

 tions; ... 



We began by asking how common sense organizes the data of ex- 

 perience. We see now that the term "experience" itself conceals 

 complexities. At the very least, the "experience" with which common 

 sense comes to grips already bears the stamp of a receptor apparatus 

 tliat— as Langer remarks— contributes actively to a rudimentary or- 

 ganization of what is received. 



A tendency to organize the sensory field into groups and patterns 

 of sense-data, to perceive fomis rather than a flux of light-impressions, 

 seems to be inherent in our receptor apparatus just as much as in the 

 higher nervous centers with which we do arithmetic and logic. But 

 this unconscious appreciation of forais is the primitive root of all ab- 

 straction, which in turn is the keynote of rationality; so it appears that 

 the conditions for rationality lie deep in our pure animal experience 

 —in our power of perceiving, in the elementary functions of our eyes 

 and ears and fingers. Mental life begins with our mere physiological 

 constitution. 



Provided with physiologically similar sensory equipment, the higher 

 apes seem to see objects somewhat as we do. Judging from their ac- 

 tions, so do far lower animals; for example, like ours, their vision 

 singles out for attention any trace of movement in a complex but 

 otherwise static visual field. Ability to see "moving objects"— objects 

 to be pursued, to be eaten, or objects to flee or to hide from— has an 

 obvious survival value. Perhaps then, by way of natural selection, 

 capacity to see "objects" comes to be a built-in feature of tlie sensory 

 organs of species successful in the struggle for life. Shaping us for 

 this particular kind of perception, our animal history thus underlies 

 the activity of common sense and science alike. 



Observing. What part of the purely physiological organization of 

 experience takes place in the sensory organ, and what part in the 

 brain, is unclear. Some of this organization, e.g., the figure-ground 

 distinction, seems to be wholly spontaneous and unlearned. But we 

 do know that visual perception involves, in addition to the immedi- 

 ate locale of the sense termini, a rather large part of the brain. Hebb 

 moreo\'er tells us : 



