376 INTRODUCTION TO PHILOSOPHY OF SCIENCE 



in recent discussion of the foundations of science. Whether 

 this distinction is purely relative and therefore not deter- 

 minative of distinctions between kinds of laws, or whether 

 it is more basic than this, is not easy to state. Unquestion- 

 ably the problem is intimately tied up with the distinction 

 between individual and statistical laws, for if an event is 

 considered to be constituted by microscopic elements it 

 behaves both as an individual and as an aggregate. But the 

 problem is too involved to be examined here. 



Furthermore, these classes of laws are not mutually ex- 

 clusive. It is possible, for example, that a law should be 

 both nomically necessary and empirically probable. Any 

 law which is an empirical generalization but which is be- 

 ginning to take a place in a rational symbolic scheme would 

 be such a law. And, as has just been seen, a law which is 

 descriptive of an aggregate (and is therefore statistical) may 

 also be descriptive of that aggregate acting as a unit, hence 

 laws of the type (c) are not sharply distinguished from those 

 of the type (b). Again the problems are too complex to be 

 examined in an elementary treatise. 



Reference may be made in a final section to a problem 

 intimately connected with this, viz., the problem of inde- 

 terminacy in nature. 



INDETERMINISM 



Recent approaches to the problem of induction differ 

 from earlier approaches, as has been seen, in an increased 

 interest in probability. It has been recognized that there 

 exists no principle called the uniformity of nature by which 

 inference to universal scientific laws may be justified. But 

 this does not involve an abandonment of the belief that 

 there are strains of uniformity in nature. Even probable 

 inferences are based on certain assumptions of constancy, 

 and it is the task of science to select these features of uni- 

 formity and to formulate them in laws. 



One of the simplest and most pervasive of the types of 

 uniformity is that exhibited in the system of classical me- 



