SCIENCE (and common SENSE ) 37 



tion as "fact" we claim to require a general concurrence of "normally 

 constituted observers." How are we to recognize those normal ob- 

 servers? Beyond the obviously enormous variation in mental charac- 

 teristics of men, the investigations of R. Williams and others demon- 

 strate that even as chemical machines men are never identical with 

 one another. Whatever the situation in the "external world," human 

 experience of it must be xariable because the experiencing hun^an 

 reporters diflFer in biochemical constitution. These differences make 

 themselves felt most notably in reports of tastes and odors. They are 

 less noticeable in reports of visual, auditory, and tactile experience. 

 Even here, however, different individuals falling within the ranee of 

 ^'normal" deviations from the average may make significantly differ- 

 ent reports. Thus Polanyi reminds us of 



. . . the famous case of the Astronomer Royal, Nicholas Maskeleyne, 

 who [in 1796] dismissed his assistant Kinnebrook for persistently re- 

 cording the passage of stars more than half a second later than he, his 

 superior. Maskeleyne did not realize that an equally watchful ob- 

 server may register systematically different times by the method em- 

 ployed by him; it was only Bessel's realization of this possibility which 

 20 years later resolved the discrepancy and belatedly justified Kinne- 

 brook. Experimental psychology, of which Bessel thus laid the 

 foundation, has since taught us universally to expect such individual 

 variations in perceptive faculties. 



Normality, then, is a fairly remote abstraction. Were we to insist 

 that "fact" must represent the rigorous agreement of "normal ob- 

 servers" we might find very few facts indeed. How to proceed? To 

 reject a deviant report or reports ex post facto, as due to "abnor- 

 mality" of the reporters, may seem essentially to vitiate the concur- 

 rence criterion. For then it is not the agreement that makes the fact 

 but we who, by forcing the agreement, in part create the fact. Had 

 we means to detect abnormality independent of failure to concur in 

 observation reports, our position would be stronger. For major ab- 

 normality such means are usually available— lunatics are often recog- 

 nizable as such and we may decline to use them as observers. Less 

 striking abnormalities may also be recognized by the exercise of 

 judgment. Proceeding in this way, most potentially deviant reports 

 might be eliminated by rejecting as qualified observers those likely 

 to give such reports. 



We can now gain the support of the profound normalizing effect 



