THE UNIQUENESS OF THE INDIVIDUAL 



astronomy has a Muse that will not do. Our leading phil- 

 osopher^ once called it 'a mere method of making plausible 

 guesses\ The word mere rankles, for it is guesswork that must 

 be imaginative, apt and technically informed. Too much learn- 

 ing may however be as dangerous as too little. Ail scientists 

 know of colleagues whose minds are so well equipped with the 

 means of refutation that no new idea has the temerity to seek 

 admittance. Their contribution to science is accordingly very 

 small. 



It is right to point out, because of the irritating mystique that 

 has grown up round it, that clinical diagnosis illustrates the 

 act of hypothesis formation in an uncomplicated and fairly 

 lucid way. The clinician seeks an hypothesis that will account 

 for his patient's illness. There is no time in the course of his 

 investigation during which some hypothesis is not in the back- 

 ground of his mind, and during its early stages there may be 

 many. If his mind ends up blank after examination, that is not 

 because no hypothesis sought admittance, but because all that 

 did so had to be turned away. The experienced clinician is very 

 well aware of the intuitive nature of the act of mind by which 

 he hits on an hypothesis, but he sometimes fails to realize 

 that this is the commonplace of scientific discovery: hence the 

 fuss. 



A scientific theory is propped up on either side, like Moses"* 

 arms before the Amalekites, by twin supports that together 

 form its ""metatheory"*, and without these Reason cannot pre- 

 vail. One part of metatheory, now called logical syntax, deals 

 with the concepts of formal truth and falsity and the ordin- 

 ances that govern the activity of deducing. Logical syntax is 

 wholly the logician's business. The second part, semantics, 

 more recent of origin and in lay circles now more fashionable, 

 deals with the theory of the meanings of words and the ideas of 

 material truth and falsity. The semantic problems of a science 

 1 Bertrand Russell: The Principles of Mathematics, p. lln, 1903. 



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