90 SCIENTIFIC INVESTIGATION 



do not know it at all ; it is nothing but an hypothesis 

 rapidly framed in your own mind. And it is an hypo- 

 thesis founded on a long train of inductions and de- 

 ductions. 



What are those inductions and deductions, and how 

 have you got at this hypothesis ? You have observed 

 in the first place, that the window is open ; but by a train 

 of reasoning involving many inductions and deductions, 

 you have probably arrived long before at the general 

 law and a very good one it is that windows do not 

 open of themselves; and you therefore conclude that 

 something has opened the window. A second general 

 law that you have arrived at in the same way is, that 

 tea-pots and spoons do not go out of a window spon- 

 taneously, and you are satisfied that, as they are not 

 now where you left them, they have been removed. In 

 the third place, you look at the marks on the window- 

 sill, and the shoe-marks outside, and you say that in all 

 previous experience the former kind of mark has never 

 been produced by anything else but the hand of a 

 human being; and the same experience shows that no 

 other animal but man at present wears shoes with hob- 

 nails in them such as would produce the marks in the 

 gravel. I do not know, even if we could discover any 

 of those "missing links" that are talked about, that 

 they would help us to any other conclusion ! At any 

 rate the law which states our present experience is 

 strong enough for my present purpose. You next reach 

 the conclusion that, as these kind of marks have not 

 been left by any other animal than man, or are liable 

 to be formed in any other way than a man's hand and 

 shoe, the marks in question have been formed by a 

 man in that way. You have, further, a general law, 

 founded on observation and experience, and that, too s 



