10 COMMON SENSE (aND SCIENCE) 



and eye collaborate in seeing. What we claim to perceive depends 

 no more on the sensitivity of the eye than on the conceptual inven- 

 tory deposited in the brain. Nowhere is this more apparent than in 

 experiments like those of which Polanyi gives us the following per- 

 ceptive analysis : 



Ames and his school have shown that when a ball set against a fea- 

 tureless background is inflated, it is seen as if it retained its size and 

 was coming nearer. This illusion seems to be due to the fact that in 

 this case we accommodate our eyes to a closer range, even though in 

 consequence the object gets out of focus. . . . These defects of the 

 quality and position of our retinal images are accepted here by the 

 eye, in the urge to satisfy the more pressing requirement of seeing the 

 object behave in a reasonable way. Since tennis balls are not known 

 to blow themselves up to the size of footballs, a ball which does so 

 must be seen as approaching us, even though in shaping this sensa- 

 tion tlie eye must override standards of correctness which it would 

 otherwise accept as binding. 



The rule that we follow in shaping the sight of the inflated ball is 

 one that we taught ourselves as babies, when we first experimented 

 with approaching a rattle to our eyes and moving it away again. We 

 had to choose then between seeing the rattle swelling up and shrink- 

 ing alternately, or seeing it change its distance while retaining its 

 size, and we adopted the latter assumption. By this way of seeing 

 things we eventually constructed a universal interpretative frame- 

 work that assumes the ubiquitous existence of objects, retaining their 

 sizes and shapes when seen at different distances and from difi^erent 

 angles, and their color and brightness when seen under varying il- 

 luminations. . . . 



In a larger perspective, the present experience of seeing the in- 

 flated ball come nearer to our eyes appears merely as the last of a life- 

 long chain of experiences encountered and shaped by us, to each of 

 which we reacted to make sense of it as best we could, and which are 

 now all subsidiarily effective in the shaping and comprehension of our 

 present experience. 



Constructs. What we may call "bare experience" already confronts 

 us with an inseparable fusion of perceptual and conceptual ele- 

 ments. For us "the given" is perhaps formed frojn sensory stimuli, or 

 percepts; but formed in the pattern of a supposed general class, 

 which is a concept. What enters consciousness Margenau calls a 

 construct. 



