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are examples of physical laws. No one doubts that they 

 express physical facts, i.e., routines of experience. Never- 

 theless they do appear in a different category from the 

 mathematical relations among symbols to which numbers 

 may be attached by means of operations performed in the 

 laboratory. These relations are the ones which we shall 

 consider as forming the class of real physical laws in the 

 sense in which the term is used in the present text." x How- 

 ever adequate such a view may be for the purpose of writing 

 a book on physics, it is hardly proper for a general logic of 

 science. One may well admit that a functional correlation 

 represents the ideal of all science, but one need not admit 

 that only ideal science is science. Clearly, carefully stated 

 qualitative laws are scientific laws in the most general sense 

 of the term. 



Furthermore, if the scope of science is limited to quantita- 

 tive laws, there is no place for those peculiar laws which 

 describe the technique of measurement itself. In a specific 

 case, for example, one may perform certain operations, the 

 outcome of which would be expressed in the judgment, 

 "The length of a certain line is 2 centimeters." This states 

 a correlation between something qualitatively given — a 

 length — and something quantitatively given — a number. 

 The generalization of this process results in a number of 

 statements which would be called the laws for the measure- 

 ment of lengths. They state the general type of correlation 

 which holds between lengths and their measured values. 

 Laws of this kind are implicit in the functioning of all auto- 

 matic measuring devices. They are not properly quantita- 

 tive laws since qualitative events enter into them. Hence it 

 seems preferable to define "scientific law" in such a way as 

 to permit the inclusion of laws of this kind. 



(2) However, although qualitative laws may occur in 

 science, they differ from empirical laws not in the character 

 of the correlation but in the care and precision with which 

 the respective elements of the law are defined and identified. 



1 R. B. Lindsay and H. Margenau, Foundations of Physics, p. 20. 



