LAW, CAUSE 375 



to whether a law is universal or less than universal is inti- 

 mately associated with the problem as to whether the law 

 is necessary or probable. An examination of the operational 

 techniques suggested that the search for laws which are both 

 universal and necessarily true has been more or less com- 

 pletely abandoned; in its stead has appeared an operational 

 route which endeavors to base universal laws — where such 

 laws are at all possible — on probabilities, and to substitute 

 for universal laws — where such laws are not possible — 

 statistical frequencies. The result of this approach is the 

 diversification of scientific laws into somewhat the follow- 

 ing types: 



(a) Laws which are universal and necessary, but whose 

 universality and necessity are determined intensionally 

 rather than extensionally. This is the status of all nomic 

 laws, which include the propositions of all "rational" sci- 

 ences, especially those laws which are called "ideal." Such 

 laws are necessary and true by virtue of the postulate sys- 

 tems from which they can be deduced, rather than by virtue 

 of empirical reference. 



(b) Laws which are universal, but only probably true. 

 This is the status of most scientific laws which are not nomi- 

 cally necessary. Such laws have a definite empirical reference 

 to examined cases through routes which describe the number 

 of instances, and the degrees of similarity and dissimilarity 

 exhibited by the instances. 



(c) Laws which state statistical correlations only, and are 

 based on examined frequencies. This is the status of all 

 scientific laws which are not of the other two types. These 

 laws also have a definite empirical reference, but to collec- 

 tions or aggregates rather than to individuals, and deter- 

 mined through routes which are descriptive of the counting 

 and sorting of cases. 



Such a classification is at least suggestive of the main types 

 of law. It is probably not exhaustive. For example, no refer- 

 ence has been made to the distinction between microscopic 

 and macroscopic laws, which has played an important part 



