4 o8 THE POPULAR SCIENCE MONTHLY, 



of y; then we find the value of y in terms of x; and so on we may continue 

 forever without coming nearer to a solution." — {Principles of Psychology, 

 § 272.) 



Carrying a little further this simile, will, I think, show where lies 

 the insuperable difficulty felt by Mr. Sidgwick. Taking x and y as 

 the subjective and objective activities, unknown in their natures and 

 known only as phenomenally manifested, and recognizing the fact 

 that every state of consciousness implies, immediately or remotely, 

 the action of object on subject, or subject on object, or both, we may 

 say that every state of consciousness will be symbolized by some 

 modification of x y — the phenomenally-known product of the two 

 unknown factors. In other words, xy\ cc'y, x'y\ x"y\ x'y'\ etc., etc., 

 will represent all perceptions and thoughts. Suppose, now, that 

 these are thoughts about the object ; composing some hypothesis 

 respecting its character as analyzed by physicists. Clearly, all such 

 thoughts, be they about shapes, resistances, momenta, molecules, 

 molecular motions, or what not, will contain some form of the sub- 

 jective activity x. Now, let the thoughts be concerning mental pro- 

 cesses. It must similarly happen that some mode of the unknown 

 objective activity, y, will be in every case a component. Now, suppose 

 that the problem is the genesis of mental phenomena, and that, in the 

 course of the inquiry, bodily organization and the functions of the 

 nervous system are brought into the explanation. It will happen, as 

 before, that these, considered as objective, have to be described and 

 thought about in modes of. x y. And when by the actions of such a 

 nervous system, conceived objectively in modes of x y, and acted 

 upon by physical forces which are conceived in other modes of x y y 

 we endeavor to explain the genesis of sensations, perceptions, and 

 ideas, which we can think of only in other modes of x y, we find 

 that all our factors, and therefore all our interpretations, contain the 

 two unknown terms, and that no interpretation is imaginable that 

 will not contain the two unknown terms. 



What is the defense for this apparently circular process ? Simply 

 that it is a process of establishing congrtdty among our symbols. It 

 is the finding a mode of so symbolizing the unknown activities sub- 

 jective and objective, and so operating with our symbols, that all our 

 acts may be rightly guided — guided, that is, in such ways that we 

 can anticipate when, where, and in what quantity, one of our symbols 

 will be found. Mr. Sidgwick's difficulty arises, I think, from having 

 insufficiently borne in mind the statements made at the outset, in 

 " The Data of Philosophy," that such conceptions as "are vital, or can- 

 not be separated from the rest without mental dissolution, must be 

 assumed true provisio?iatty / " that "there is no mode of establishing 

 the validity of any belief except that of showing its entire congruity 

 with all other beliefs," and that "Philosophy, compelled to make 

 those fundamental assumptions without which thought is impossible, 



