SCIENCE (and common SENSE ) 47 



culty can we come to feel at ease with these late acquisitions, and 

 with the exotic language in which they are expressed. We may then 

 be led to compare scientific concepts unfavorably with the "natural" 

 concepts of common sense. This is nonsense, for, as Einstein obsers^es: 



Physical concepts are free creations of the human mind, and are 

 not, however it may seem, uniquely determined by the external 

 world. 



When the task is different, the most appropriate conceptual tool 

 may well be different. Thus, for example, if through the indicative 

 concepts of common sense we arrive at predictively powerful colliga- 

 tive relations, those concepts fully discharge the function for which 

 they were devised. But these relations of common sense do not lend 

 themselves to the fourth stage of organization sought in science. And 

 so in science we seek, through indicative concepts expressly designed 

 with this different function in mind, for relations that do so lend 

 themselves. For conceptual evolution common sense and science thus 

 constitute two distinct though overlapping domains, imposing dis- 

 tinct though related demands. The everyday concepts, enormously 

 successful in the domain of common sense, do not thereby establish 

 any claim to fitness for survival in the domain of science. Because the 

 motions of swimming are useful in propelling us through water, it 

 does not follow that we do best to breast-stroke along the beach. 



Devices of men bent on the quest for a comprehensive rational 

 order in experience, the concepts of science fall subject to natural 

 selection in the world of man's experience. How by "natural selec- 

 tion"? The scientific concept "cell" is a thing-concept that synthesizes, 

 from various perceptual elements, a "something." Like the common- 

 sense concept of "physical object," "cell" refers also to a conspic- 

 uously abstract something: an extraordinary variety of actual forms 

 are all grouped under the rubric of one diagrammatic representation 

 of a typical cell. In both cases the concrete value of the abstract con- 

 cept is abundantly demonstrated, however, as we find that what it 

 joins together can, in thought or in action, be handled effectively as 

 SL something. Passing on to class-concepts, we encounter here the 

 traditional tools of classification so richly represented in the endeav- 

 ors of biologists and geologists. A less hackneyed example, perhaps, 

 is the chemist's concept— "carbon"— which holds fundamentally iden- 

 tical substances as different as charcoal, graphite, and diamond. Such 



