64 The Scientific Method. 



servation of the universe convinces me that the sun revolves 

 about the earth ; I see it rise in the east, traverse the sky, 

 and set in the west. The inference of my own thought 

 from my own observation is that 'the sun do move.' 

 Against this thought of mine you have nothing whatever 

 to oppose except your own thought ; but one individual's 

 thought is just as much knowledge as another's. You may 

 multiply your mere thought by a thousand million, but that 

 does not make it either ignorance or knowledge. Individu- 

 als differ just as much in their observations as in their in- 

 ferences ; and there is no judge, no criterion of knowledge, 

 to appeal to in either case. Hence your ' facts of the uni- 

 verse ' exist only as my own observations and inferences 

 in a word, as my own thoughts ; and it is inane for you to 

 appeal from my thoughts to my thoughts, as if you could 

 array me against myself. 



" But this is not all ; I go still further. What do you 

 mean by your ' universe ' anyhow ? You mean a real ex- 

 ternal world, wholly outside of your own consciousness, and 

 wholly independent of it. It is absurd to postulate any 

 such world as that. If there is any truth whatever in the 

 doctrine of the relativity of knowledge (which you will not 

 venture to call in question), you can not possibly know 

 anything whatever of an external world. You can only 

 know certain changes or affections of your own conscious- 

 ness, caused you can not tell how. The individual mind 

 can know nothing but its own changing states of conscious- 

 ness. It can never know anything external to those states. 

 All its observations, all its inferences, all its knowledge, all 

 its ignorance, lie solely within the sphere of that conscious- 

 ness, and have no meaning at all Avith reference to any ex- 

 ternal world lying beyond that sphere. In fact, to be per- 

 fectly candid, I am bound to deny, and I do deny, the very 

 possibility of any external world beyond my own individual 

 mind ; for, if I admit that an external world may possibly 

 exist and that I may yet be ignorant of it, I thereby con- 

 tradict my fundamental principle that knowledge and igno- 

 rance have no possible reference to anything outside of in- 

 dividual consciousness. If knowledge is nothing but thought 

 (and who disputes that?), then ignorance, the absence of 

 knowledge, can only be thoughtlessness, the absence of 

 thought can only be unconsciousness, the absence of con- 

 sciousness. If knowledge were thinking rightly, then igno- 

 rance would be thinking wronyly ; but this would imply a 



