338 METHODOLOGY OF SCIENCE 



minor premise. Actually the method of reasoning is essentially 

 different, for the minor premise is not obtained by showing that all 

 the elements of the concept M are found in C, but only some of them. 

 The conclusion is not necessary, but only probable, and the whole 

 process of reasoning runs : Certain elements are frequently found to- 

 gether, therefore they are united in the concept M. Certain of these 

 elements are recognized in the thing C, therefore probably the other 

 elements of the concept M will be found in C. 



The old logic, also, was familiar with this kind of conclusion. It 

 was branded, however, as the worst of all, by the name of incomplete 

 induction, since the absolute certainty demanded of the syllogism 

 did not belong to its results. One must admit, however, that the whole 

 of modern science makes use of no other form of reasoning than 

 incomplete induction, for it alone admits of a prediction, that is, an 

 indication of relations which have not been immediately observed. 



How does science get along with the defective certainty of this 

 process of reasoning? The answer is, that the probability of the 

 conclusion can run through all degrees from mere conjecture to the 

 maximum probability, which is practically indistinguishable from 

 certainty. The probability is the greater the more frequently an 

 incomplete induction of this kind has proven correct in later experi- 

 ence. Accordingly we have at our command a number of expressions 

 which in their simplest and most general form have the appearance : 

 If an element A is met within a thing, then the element B is also 

 found in it (in spatial or temporal relationship). 



If the relation is temporal, this general statement is known by 

 some such name as the law of causality. If it is spatial, one talks of 

 the idea (in the Platonic sense), or the type of the thing, of substance, 

 etc. 



From the considerations here presented we get an easy answer 

 to many questions which are frequently discussed in very different 

 senses. First, the question concerning the general validity of the 

 law of causality. All attempts to prove such a validity have failed, 

 and there has remained only the indication that without this law 

 we should feel an unbearable uncertainty in reference to the world. 

 From this, however, we see very plainly that here it is merely a 

 question of expediency. From the continuous flux of our experiences 

 we hunt out those groups which can always be found again, in order 

 to be able to conclude that if the element A is given, the element B 

 will be present. We do not find this relationship as "given," but 

 we put it into our experiences, in that we consider the parts which 

 correspond to the relationship as belonging together. 



The very same thing may be said of spatial complexes. Such factors 

 as are always, or at any rate often, found together are taken by us as 

 "belonging together," and out of them a concept is formed which 



