EXACTITUDE ATTAINABLE IN BIOCHEMISTRY 23 



more extensive, the width of the margin of inexactitude diminishes, and 

 that is all. For example, no "law" is apparently of more extensive 

 applicability or capable of more precise mathematical formulation 

 than Newton's law, that bodies attract one another as the inverse 

 square of their distance apart. Yet certain astronomical data, devia- 

 tions in the orbit of the planet Mercury, 1 point to the possibility that 

 even this law may not be exact and that the true exponent of the 

 distance may in truth not be 2 but 2.000,0001612. The margin of 

 inexactitude is here represented by the minute fraction 0.0000001612, 

 but it is here nevertheless. And so it is with all scientific hypotheses. 

 Our laws, formulations and hypotheses are merely temporary short- 

 hand statements of our acquaintance with the facts. As our acquaint- 

 ance with the facts grows larger we must revise our shorthand to express 

 our accessions of knowledge. The shorthand is not the knowledge 

 itself. Science, in reality, consists solely in our knowledge of facts and 

 our control of the forces of nature and not of the hypotheses which we 

 formulate by the way in order to summarize our present state of 

 knowledge and stimulate the imagination to fresh inquiries. Biology 

 is, in truth, no less an "exact" science than any other, than astronomy, 

 for example, but its hypotheses are subject to much more frequent 

 and thorough revision than those of physics or astronomy, simply 

 because our knowledge of the field is less and is growing more rapidly. 



The whole theory of the scientific method of thought has in fact 

 been based by the great founders of science upon the assumption of the 

 fallibility of purely intellectual operations, and hence of the untrust- 

 worthiness of hypotheses. Newton's famous rule, " Hypotheses non 

 fingo," while impracticable for the individual investigator, remains 

 nevertheless true of science as a whole, of the body of exact knowledge, 

 that is, which endures the test of time and endows mankind with the 

 power of ruling and directing the multifarious and stupendous forces of 

 Nature. During the centuries which have been marked by the acquire- 

 ment of this knowledge countless hypotheses have been formed, and 

 accepted for a while, and then abandoned as evidently absurd. But 

 the forward march of exact knowledge has never suffered interruption 

 and not infrequently indeed has been very much facilitated by the 

 most obviously erroneous hypotheses. The phlogiston theory of heat 

 is perhaps the most striking example of this kind. It was a most 

 patently erroneous hypothesis, built up by perfectly sound reasoning 

 based upon imperfectly understood facts. Yet for a hundred years 

 the mere existence of this hypothesis was the greatest contemporary 

 stimulus to the development of chemistry and it ultimately led to the 

 establishment of the conception of the conservation of matter. 



As the curves of the geometrician approach and yet never actually 

 attain their asymptote, so do we continually approach and never yet 

 have we attained the utter truth. The merit of the scientific method 



1 Cf . article on Gravitation, Encyclopedia Britannica, 1 1th edition. 



