250 NOTES AND COMMENTS [ocroBER 
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 
elad 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, eg. 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, 

