250 NOTES AND COMMENTS [october. 



Scientific Explanations. 



The progress of science is continually hindered by the limitations of 

 language. What a bugbear, for instance, has been the word " law " — 

 an innocent metaphor to the careful, but an inhibiting fallacy to the 

 many. For, as every one knows, the " laws of nature " were for many 

 decades the subjects of naive personification, and made to will and act 

 as self-sufficing governors of phenomena, while now, as Professor J. H. 

 Poynting remarked in his opening address to Section A of the British 

 Association, " we can only assign to them the humble rank of mere 

 descriptions, often tentative, often erroneous, of similarities which 

 we believe we have observed." It is indeed a fall of the mighty. 



But though the word " law " has almost ceased from troubling, 

 there remain many others which still exert their pernicious influence. 

 Prominent among these is the word " explanation," at which we are 

 glad to see that Professor Poynting has also made some deadly thrusts. 

 Thickly scattered through scientific literature the student finds what 

 are called " complete explanations," but occasionally he is confronted 

 with the strange remark that science does not give any explanations 

 at all. What does it mean ? 



The meaning is simply that while the teleological idea (of " final 

 cause," etc.) is essential to any attempt at a complete or philosophical 

 consideration of facts, e.g. to a theory of the living organism, it is 

 irrelevant and inhibitive in scientific inquiry, which is strictly aetio- 

 logical. But let Professor Poynting speak for himself. 



" We have not to go very far back to find such a statement as 

 this — that we have explained anything when we know the cause of it, 

 or when we have found out the reason why — a statement which is 

 only appropriate on the psychical view. Without entering into any 

 discussion of the meaning of cause, we can at least assert that that 

 meaning will only have true content when it is concerned with purpose 

 and will. On the purely physical or descriptive view the idea of cause 

 is quite out of place. In description we are solely concerned with the 

 ' how ' of things, and their ' why ' we purposely leave out of account. 

 We explain an event, not when we know ' why ' it happened, but 

 when we show ' how ' it is like something else happening elsewhere, 

 or otherwise — when, in fact, we can include it as a case described by 

 some law already set forth. In explanation, we do not account for the 

 event, but we improve our account of it by likening it to what we 

 already know. . . . The aim of explanation, then, is to reduce the 

 number of laws as far as possible, by showing that laws, at first 

 separated, may be merged in one ; to reduce the number of chapters 

 in the book of science by showing that some are truly mere sub- 

 sections of chapters already written. ... To take an old but never- 

 worn-out metaphor, the physicist is examining the garment of nature, 



