LAW, CAUSE 365 



devising of a postulate system, for any law which can be 

 derived from such a system becomes true no matter what; 

 i.e., its truth becomes of an intensional kind which is de- 

 pendent merely upon a symbolic scheme, and independent 

 of empirical reference. All laws of pure mathematics, all 

 laws of rational mechanics, and many of the laws of physics 

 are necessary in this sense. Since the attribution of nomic 

 necessity to a law is an arbitrary act, any law in any science 

 may become nomically necessary. V. Stefansson * argues 

 that the definition of an ostrich as a bird which buries its 

 head in the sand when pursued, even though there is no such 

 bird as this, has some advantage over the definition in terms 

 of biological properties. Since most people believe that the 

 ostrich does this, such a definition would have social ap- 

 proval. A new term could then be invented to name the 

 biological specimen. This illustrates clearly the relation 

 between a law which is empirically necessary and one which 

 is nomically necessary. Usually, however, the development 

 of a postulate system is required to give sufficient stability 

 to the intensional definition of the concept entering into the 

 law. The future of the biological and humanistic sciences 

 presumably lies in the development of postulate systems 

 and the emergence of more and more laws which are nomi- 

 cally necessary. 



The operational derivation of scientific law may be sum- 

 marized in the following terms: An empirical law becomes 

 scientific through measurement, which replaces vaguely 

 described qualitative events by precisely designated quanti- 

 tative events; through a complex operation involving gen- 

 eralization, interpolation, and approximation, which results 

 in a further refinement; and, finally, through such activities 

 as the multiplication of cases, the ascertainment of the degree 

 of analogy applying to them, the determination of frequen- 

 cies, and certain acts of arbitrary fiat — all of which replace 

 a vaguely grasped empirical necessity by more or less pre- 

 cise statements of probability and necessity. These state- 



1 The Standardization of Error (New York: Norton, 1927), p. 17. 



