SCIENCE (and common SENSE ) 45 



to my assistant who understands my language, he will know I mean: 

 Does the spot move? and he will look at the scale. 



Observe the perfect parallelism of this and a common-sense situation 

 sketched by Herschel: 



In Captain Head's amusing and vivid description of his journey 

 across the Pampas of South America occurs an anecdote quite in 

 point. His guide one day suddenly stopped him, and, pointing high 

 into the air, cried out, "A lion!" Surprised at such an exclamation, ac- 

 companied with such an act, he turned up his eyes, and with diffi- 

 culty perceived, at an immeasurable height, a flight of condors soar- 

 ing in circles in a particular spot. Beneath that spot, far out of sight of 

 himself or guide, lay the carcass of a horse, and over that carcass stood 

 (as the guide well knew) the lion, whom the condors were eyeing 

 with envy from their airy height. The signal of the birds was to him 

 what the sight of the lion alone could have been to the traveler, a 

 full assurance of its existence. 



The scientist's constructs carry no small burden of inference: see- 

 ing a spot of light, he "observes" (and reports) an electric current. 

 The scientific constructs diflFer from those made by common sense 

 in the nature of their inferential freight, perhaps also in the reduced 

 magnitude of their freight of unconscious inference. But of this there 

 is always some. Braithwaite conceives that: 



The peaks of [theoretic] science may appear to be floating in the 

 clouds, but their foundations are in the hard facts of experience. 



Popper proposes a related metaphor w^hich, however, finds "softness'^ 

 in Braithwaite's foundations : 



The empirical basis of objective science has thus nothing "absolute" 

 about it. Science does not rest upon rock-bottom. The bold sti-ucture 

 of its theories rises, as it were, above a swamp. It is like a building 

 erected on piles. The piles are driven down from above into the 

 swamp, but not down to any natural or "given" base; and when we 

 cease our attempts to drive our piles into a deeper layer, it is not be- 

 cause we have reached fiiTn ground. We simply stop when we are 

 satisfied that they are firm enough to carry the structure, at least for 

 the time being. 



The towering structure of theoretic science is then stable only as, 

 from time to time, scientists of the calibre of Aristarchus or Coperni- 



