44 SCIENTIFIC METHOD IN PHILOSOPHY 



information, since it tells us that certain known objects 

 are related according to a certain known form. Thus 

 some kind of knowledge of logical forms, though with 

 most people it is not explicit, is involved in all under- 

 standing of discourse. It is the business of philosophical 

 logic to extract this knowledge from its concrete integu- 

 ments, and to render it explicit and pure. 



In all inference, form alone is essential : the particular 

 subject-matter is irrelevant except as securing the truth 

 of the premisses. This is one reason for the great im- 

 portance of logical form. When I say, "Socrates was a 

 man, all men are mortal, therefore Socrates was mortal," 

 the connection of premisses and conclusion does not in 

 any way depend upon its being Socrates and man and 

 mortality that I am mentioning. The general form of 

 the inference may be expressed in some such words as, 

 " If a thing has a certain property, and whatever has this 

 property has a certain other property, then the thing in 

 question also has that other property." Here no particu- 

 lar things or properties are mentioned : the proposition 

 is absolutely general. All inferences, when stated fully, 

 are instances of propositions having this kind of generality. 

 If they seem to depend upon the subject-matter otherwise 

 than as regards the truth of the premisses, that is because 

 the premisses have not been all explicitly stated. In 

 logic, it is a waste of time to deal with inferences concern- 

 ing particular cases : we deal throughout with completely 

 general and purely formal implications, leaving it to 

 other sciences to discover when the hypotheses are 

 verified and when they are not. 



But the forms of propositions giving rise to inferences 

 are not the simplest forms : they are always hypothetical, 

 stating that if one proposition is true, then so is another. 

 Before considering inference, therefore, logic must con- 



