40 WHAT IS SCIENCE? 



why and where scientific and popular usage differ. 

 Accordingly, in the rest of this chapter we shall examine 

 the matter more closely. 



THE DEVELOPMENT OF LAWS 



First, we may note that there is an apparent difference 

 between the popular conception of the part played by 

 laws in science and that laid down by our definition. It 

 is probably usually thought that it is the aim and object 

 of science to discover laws, that laws are its final result. 

 But according to our view nothing can be admitted 

 to the domain of science at all unless it is a law, for it is 

 only the relations expressed by laws that are capable of 

 universal agreement. Laws are the raw material, not 

 the final product. There is nothing inconsistent in these 

 two statements, but the mode in which they are to be 

 reconciled is important. Laws are both the raw material 

 and the finished product. Science begins from laws, and 

 on them bases other laws. 



To understand how this may be let us take an example 

 of a law ; that used already is not very suitable for the 

 purpose ; the following will serve better : A steel object 

 will rust if exposed to damp air. This is a law ; it states 

 that if one event happens another will follow ; although 

 it is the result of common observation, it would usually 

 be regarded as lying definitely within the province of 

 science. But now let us ask what we mean by a steel 

 object, or by " steel." We may say that steel is a hard, 

 shining, white substance, the hardness of which can be 

 altered by suitable tempering, and which is attracted by 

 a magnet. But, if we express what we mean by steel 

 in this way, we are in effect asserting another law. We 

 are saying that there is a substance which is both shining, 

 white, and capable of being tempered, and attracted by a 

 magnet ; and that, if it is found to be white and capable 

 of tempering, then it will be magnetic. The very idea of 



