given and seeks to explain its origin. He does so by assuming the 

 existence of spirits with certain powers. Like the mind of Locke's 

 theory, these spirits are not things directly manifest in experience; 

 and no experiments were performed yielding evidence of their existence 

 or of their powers. The fact of the existence of spirits and of their 

 powers is purely hypothetical, and by these hypotheses supernormal 

 knowledge is explained. 



The difference between the use of assumption in Locke's and 

 Hyslop's theories and its use in the theory of ions and of the electrical 

 nature of matter, a difference which will be fully considered later, 

 should here be noted. In the theory that matter is electrical and in 

 the theory of ions, the assumption is only of the existence of things 

 like things in experience. Concretely in the theory that matter is elec- 

 trical, it is assumed that electricity exists in the form of matter; 

 and in the theory of ions, it is assumed that the atom consists of a 

 certain arrangement of ions. It was not necessary to assume what the 

 qualities of electricity are and it was not necessary to assume what 

 would result from the certain arrangement of ions; these both were 

 experimental facts. For this reason we found that assumptions in 

 these theories had great explaining power and that the explaining 

 power was evidence of the validity of the assumptions. Contrast 

 the situation in the theories of Locke and Hyslop. Here the assump- 

 tion is of the existence of things out of experience like no things in 

 experience. Concretely, in Locke's theory minds were assumed to 

 exist, and in Hyslop's spirits. From the fact that the assumed things 

 were like nothing in experience, the powers of these things were not 

 known, as they were in the case of the theory of ions, and of elec- 

 trical matter. Hence it was necessary for Locke to assume that the 

 mind had certain powers and qualities, and for Hyslop to assume that 

 spirits had certain powers and qualities. Then, when these powers 

 or qualities were manifested in experience, it could not be inferred 

 that the assumed mind or spirits existed; for it was not known, but 

 only assumed, that minds or spirits, as the case may be, could pro- 

 duce such manifestations. Thus the explaining power of the as- 

 sumptions made in Locke's and Hyslop's theories did not lead to an 

 inference of the validity of those assumptions; while as we have 

 seen, in the theory of ions and the theory of matters electrical nature, 

 it did so lead. 



From the fact that the qualities and powers of minds and spirits 

 are assumed in the theories of Locke and Hyslop, and from the fact 

 that minds and spirits are assumed to be things unlike anything in 

 experience, there is no limit to the powers or qualities that may be 

 ascribed to minds or spirits, as the case may be. If by ascribing a 



[16] 



